Part one of two:
There's many ways to go about cleaning your computer of remnants of software no longer wanted. A tedious and time-consuming manual method that I use on occasion is:
1- Use the uninstaller made by the publisher.
2- Look in the Program Files, Documents & Settings, Applications, Local Settings, and Temp areas for remnants of the program based on the publisher's name or the program's name. For example, Java might be under Java, or Sun.
3- Search through the major system directories like Windows, Documents, and Programs for all recently changed files, reconcile the newly created ones with the program being unstalled. Once you have a correlation you copy them to a s**t JumpDrive for safe keeping in case you made a mistake
4- Examine the shortcuts and where they point to, this gives clues as to where the program and misc help files might reside. Typically the Program Files directory.
5- While using the program I'll check to see if it makes logs, or where it sets up profiles and stores user generated data. That's another area to be inspected.
6- I use an old program (still available from majorgeeks) called Reg Cleaner 4.3 to perform an INSPECTION ONLY. It looks at the last known good copy and the current copy, and points out the differences. I use it in discovery mode only to give me an idea if there were new entries made. And that's it. I can then evaluate them by looking at them in the registry editor and choose to delete them then. I generally look for publisher names, program names, author names, things like that.
7- I'll often visit the nefarious warez sites to read about activations and cracks and things like that. Especially if I'm trying trialware that expires in X amount of time. Oftentimes publishers will leave a hidden mark or entry or file or something someplace that doesn't abide by common sense. This is done to prevent you from uninstalling and reinstalling for the intent of extending a trial period.
And that concludes the manual way of doing things. Tedious, time consuming, and requires experience on how programs interact with the O/S and how things are put-together in general.
Part two of two:
There's a lot of ways to be even more effective than what I just listed. But these methods require some activity on your part prior to installing anything. They are easier, far less tedious, and take a side-step backdoor approach to the problem.
1- Use a virtual machine. When you are done with testing and evaluating, you just delete the machine and create a new one. Or copy the .VHD you have in protective store. Thus always having a pristine config ready to go. This is very much akin to disk imaging.
2- Use Revo Uninstaller. This does pretty much what I did in part one. With the added advantage of overseeing the install process from the get-go. This is much like RollbackRX.
3- Use RollbackRX. This is like an instant Apple TimeMachine. Except that instead of backing up your disks, it rearranges the disk's sector map. I've evaluated this for a long time and deem it to be surprisingly stable and resistant to abuse like inopportune power offs. This also recovers instantly from a lot of malware. This behaves like an always-on Revo Uninstaller, except it tracks each and every file. Disks become very fragmented with this, so it is suited to SSD rather than HDD. This is popular on public access terminals and kiosks. You can randomly go through and corrupt and delete parts of your OS. And roll the system back to 1-hour ago, error free. This is amazingly easy to use and just plain works. I've even tested it with mal-ware infections to good effect.
4- My favorite, disk imaging. Before I go and start installing stuff and updating things. I just take a disk image. Any screw-ups or if I don't like what I installed, I just restore.
5- Use old school computers that don't need software installations, like the Apple II. Just kidding.
6- Go with dumbed-down tablets. All these things work with 1 or 2 button presses. And if anything goes bad, you hit the master reset and start over.