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Registry cleaning is a bit of a black art. There's no real consensus on cleanliness, and different programs will often return different results.

Let's say you download the so-called top two registry cleaners. You perform a scan with the first, and allow it to clean the errors.

Now you use the "other" cleaner, run a scan and it shows hundreds of errors.

Back to the first, scan again and it still shows zero errors.

I'm beginning to think these cleaners are all made up and only show errors until you purchase the product. Once you do so they then show that they "did their job" and that your computer is in great shape after the scan.

What's your take?

I have mixed feelings about registry cleaners in general, and one reason is that there are indeed less-than-reputable companies who are indeed doing things much like you suspect, and worse.

However there are several very legitimate products, and guess what? You'll get different results between them as well.

The reason may surprise you.

First, I need to be up front and let you know that some of the companies that create and sell registry cleaners and optimization programs are occasional direct (i.e. non-Google) advertisers here on Ask Leo!. I say that up front to hopefully avoid concerns that I might be influenced by them, and to allow you to make your own decisions well-informed.

Ads that show up in the Google ad blocks are, largely, out of my control, but I only accept direct advertising from companies that I believe are relatively reputable.

But that doesn't imply that I think that their products are always necessary. Smile

In fact my stance on registry cleaners is pretty clear: 99% of the time I don't think they're needed at all.

"... there's actually no definition of what it really means for the registry to be 'clean'."

So, why might different registry cleaners return different results?

In short, because there's actually no definition of what it really means for the registry to be "clean".

Oh, there are some obvious things, like perhaps references to files and software that no longer exist. But the bottom line is that the registry is such a complex collection of data that it's nearly impossible to encapsulate all the rules of what can and cannot be cleaned, what's safe to remove and what's not, into a single cleaning program.

This concept of "safe" is also a very important difference. It's not always obvious whether a particular cleaning action will, in fact, be safe and not have unintended side-effects. Many registry cleaners will allow you to specify how "aggressive" they are to be, and others simply select a particular level of what they feel is reasonable.

Neither are wrong, but neither can be completely right either. It's just not that simple.

And it's another source of differences between the different products.

The model of telling you what's wrong for free but then charging you to fix it is, in fact, a legitimate sales approach. Unfortunately it's also abused by various malware and other companies to occasionally scare you into buying things you don't need, or worse, installing malware on your machine.

So how do you tell what's what?

In my opinion it's all about reputation. Do a little research and see what independent (and again, reputable) third party sites report on various tools. See what discussion groups say. Even my article that says that registry cleaners aren't typically needed includes a couple of recommendations.

To further complicate matters, purveyors of malware and disreputable tools appear to be very good at deception. Take care that you aren't reading "planted" testimonials, watch out for "sound-alike" product names, and other scams.

But the bottom line is that as long as you take care to find and use reputable products, and follow their instructions, taking care to always backup first, you should be fine.

Even if the reputable products give different results from each other.

Article C3351 - April 15, 2008 « »

Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

April 17, 2008 3:24 AM

Hmmm...i think you are correct in saying that Reg Cleaners are not "Typically" required, but in my opinion, there are cases when a "gud' and reliable Reg Cleaner is atleast clean some malware entries....

David Hawkins
April 18, 2008 11:37 PM

On the recommendation of a friend I used CCleaner which seemed to find quite a lot to remove and after the first time I used it my PC worked fine. The second time I used it, using the same settings it must have got more agressive and the next time I tried to boot up I got nothing and had to seek help to reinstall (Thank goodness for a backup on an external hard drive.
I was told the probable reason was that CCleaner got a bit too enthusiastic and took something out of the registry which it should not have. So you can guess where that particular program got sent.


M.F.Y Badat
April 19, 2008 12:47 AM


Lynn Beeler
April 19, 2008 10:37 AM

I use RegSeeker (a free program) for my registry cleaner. In the several years that I have used Regseeker, it has never caused me any problems, and I have a high confidence level when using RegSeeker. It also has a back up feature that I feel is very important for any registry cleaner. That said I have Widows XP, SP2, for my OS and I install and uninstall a lot of software like utilities, upgrades, new versions and PC games. Many uninstall programs do not fully uninstall their product from the registry. A registry cleaner is a good way to see what is left over from uninstalls and remove the left overs from the registry. My goal is to keep the registry as small as possible as one factor in many for a faster running PC.

I also use and like CCleaner, but mostly just to remove internet and temp files.

July 13, 2010 2:44 AM

you can try this one:

William Strandwitz
April 19, 2011 5:56 AM

What about the use of registry defraggers?

In my opinion I don't see much value.

George Burrell
April 19, 2011 3:22 PM

I have been using "eusing free registry cleaner" for some years. I have also used their registry defragger. I have had no problems with it. Anyone else have a view on this one please>

April 19, 2011 9:52 PM

Having tried several registry cleaners to deal with a sluggish Windows XP fraught with problems, from suites to simple ones, I've had disasterous results from some and pleasant surprises from others.

CCleaner came by recommendation from PC World and CNET which gave it some credibility. It did little, if any, damage and seemed to clean up temporary and deleted files more efficiently than the built-in Windows disk cleanup. It backsup at your "ok" before each registry cleanup. Recently they have added a "Wipe Free Space" feature to the cleanup function that I used the last time I reformated the hard drive and anytime I have installed or uninstalled numerous programs. It significently improved the performance of the computer and gives noticeable results any time I run it. Unfortunately, it takes quite a bit of time to wipe the free space because the unused disk space is quite large on this computer. It is donation-ware, but I think it is an excellent utility for use with Windows.

April 23, 2011 9:12 PM

I use ccleaner. Its reliable and good.

May 13, 2011 3:07 PM

I've been using "Easy Clean" & "Reg Supreme" for years (winxp pro sp3) without any issues whatsoever.
They are quick, easy & simple (small footprint).
I run EC first and then RS to get what isn't picked up.
-RS also has the option to defrag/compress the registry without issue-
I'll trust my experience over any supposed expert opinion any day...

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