First, what is a stealth install? It's my term for an installation of a program or part of a program, without your knowledge, particularly when that software cannot be removed by uninstalling the program.
Let me give you an example. I have been using Corel Paint Shop Pro since before Corel bought it ... since it was Jasc's Paint Shop Pro.
When Paint Shop Pro XI (renamed Paint Shop Pro Photo) came out, I naturally upgraded. It was bad enough that a JPG file that I could open in Microsoft Paint failed to open (although Paint could open it just fine), but then I installed the 11.11 patch.
Usually after installing I check to see if anything new was installed into the startup folder, or in the startup items list, using MSCONFIG. When I did this I noticed a new service, Protexis Licensing, running.
A little research, including backing up to an old system image I had created with True Image and I realized it was the 11.11 patch that had installed this.
There were two things I was upset about: I don't like services running all the time sucking up resources and CPU power (no matter how little) when they are not needed, and I could NOT uninstall the files. After uninstalling PSP 11, they were still there in the c:windowssystem32 folder. And although I found and confirmed likely suspect files (PSIKEY.DLL and PSISERVICE.EXE), I was not 100% sure these were all the files that belonged to this licensing software.
Don't get me wrong: my copy of PSP11 is legal. I don't object to licensing software per se. I just object to extra stuff running since I am a gamer and want minimal interference when running a game that sucks my PC dry anyway. And if the program does not clean up when uninstalling, it means your hard drive gets cluttered up, even if you uninstall.
Additionally, I found that disabling the service (using SERVICES.MSC) would not prevent PSP 11 from running, nor would removing the files (either deleting or renaming them). So what good is it, and what exactly is it doing?
I looked through Corel's website and discovered they have a program called ZAPPS that's supposed to completely remove PSP. Nope, still left those files around. Grrr.
Finally I filed a tech support case. They first did not understand what I was talking about (my guess is Corel did not update their TS on this issue) and finally they told me to call them. Which, based on past experience with any tech support department, will likely result in me telling them what to do, as frankly, I usually know more than most tech support departments, based on my years in the industry.
I gave up. I went back to an older image, bought PhotoImpact 12 after confirming it did not install any licensing stealth software, and felt much more satisfied.
One other thing. During the experiments of installs / uninstalls, I found a program called Advanced Uninstaller Pro 2006 that monitors installs and thus can also completely uninstall them, even with stealth installs like this. If you're concerned about stuff like this -- and you should be, if you want a clutter-free hard drive, I would recommend you look into this program. I used a trial version, but I'll be buying it.