I don't have much experience uninstalling add-ons. For one thing, I've never been short on space yet or dis-satisfied with a product but mostly I install manually (freeware) so it's not easy to track what I install. I just dump Effects, Gauges, Sounds, etc into the folders and forget about them. If I really need to clean up later on down the road I guess I can check the original .zip files to see what was placed and what I can delete when I remove an aircraft. However if I'm dealing with a paid add-on that uses an installer program to place files in the Effects, Gauges and Sounds folder in addition to the SimObjects folder, and then I also use the included uninstaller program to remove the add-on, should it not then delete all the files it installed on my machine? Especially when I get a dialog box popping up at the end telling me the add-on has been removed from my system with no mention of any files being left behind? Imagine my surprise when I find it left just under 17MB of files that it installed on my disk in the Effects, Gauges and Sounds folders. To make double sure, I installed it in a separate folder from the default FSX install then immediately uninstalled it - all the aircraft folders were removed along with the custom scenery folder but everything else stayed. So 17MB isn't really a huge deal in this day and age - I guess I'm mainly annoyed that it didn't tell me there were still files left behind. I have experienced uninstallers in the past for other applications that have ended with a dialog box informing me that not all folders were deleted and that there might still be files left in <list of locations>. This, IMO, is a nice thing to know. So is this common for FSX add ons?

It's very common. Basically, many uninstallers will leave some files behind just in case the application is re-installed, so that when you restart the application again after re-installing it, many of your personal configuration settings, saves, preferences, etc. will still be intact. Sometimes you will be saved from having to re-enter installation registration keys because it is already saved in one of the files left behind. Some aircraft addons, though, might remove the aircraft from the SimObjects folder when uninstalled, but other stuff may have been added to FSX's Gauges and Effects folders when that aircraft was first installed, and depending on how the uninstaller is scripted those items may or may not get removed when the aircraft is uninstalled. Files might be left in the FSX installation root directory, your documents folder, or your appdata folder. Some files will even be left in you system folder, though you don't want to mess around in there unless you really, really know what you are doing - and windows sometimes won't allow you to do anything to those unless you know how to take ownership of system files - but I digress... Revo Uninstaller is a good tool to use if you want to completely remove an application and all traces of it.

Figured. Like I said though the main annoyance is that I'm not told of this.

Some of those items left behind could be "common" files shared across several products (ie a common gauge package that several addon aircraft use, etc) - in this case, uninstalling the "common" files could break other installed addons. This is fairly common in regular software as well - if you install Visual Studio on a machine that didn't have any .Net runtime installed, then uninstall Visual Studio, you will find the machine still has the .Net runtime instlaled (granted, in this case, the .Net runtime does show up in the installed programs list as a seperate item) Tim

Honestly I more annoyed by installer programs that overwrite certain "common" files with older copies... ...the most common of which is FSUIPC! It's a fairly trivial matter to script the installer to only install a specific file only "if newer" than the version the user currently has installed. Now flipping that around, it is most certainly not a trivial matter to decide whether to remove a file when uninstalling. It's a major PITA to write an intelligent uninstaller that can keep track of what was installed versus what was "skipped over" and not installed...

Yup, which is why I prefer manual installation. If the app is packed in an installer I'd have it install everything to a dummy folder first and take a look at what's going where before committing it, then once I'm satisfied I'd back up original files as necessary and manually copy the files to where they need to go. I've been stung too many times by installers - freeware ones in particular - inserting extra "gifts" that I don't care for or overwriting something I need. Most reputable apps with installers are OK (Flight1, FSGenesis, etc.), it's just the little independent and freeware ones to be wary of.