SIMBL allows patching of applications with plugins to extend their capabilities. This may interfere with certain other programs to the extent that the cure could be worse than the disease, but that depends entirely on the configuration of the Mac used, and is something to be experienced/decided by each user. But if you don't need any SIMBL-based hacks, there's no reason to have it installed.
Still, while uninstalling SIMBL may be appropriate in certain situations, a blanket advise to delete it is excessive. If necessary, however, the best way to go about deleting SIMBL is to use the Uninstaller that comes with the SIMBL package (found
here). SIMBL plugins may come with a copy of the SIMBL package, but AFAIK they have to be installed separately. There *should* be no need to dig into the guts of a plugin installer package to detect it.
In case the Uninstaller causes problems, below are the locations where SIMBL, its plugins and (occasionally) scripting controls are found:
/Library/InputManagers/SIMBL
/Library/Application Support/SIMBL/Plugins
/Library/ScriptingAdditions/SIMBL.osax
Note that you may not have all of the above, but it probably won't hurt to check these locations in your user accounts (~Library) as well.
PS, 500 Mb of virtual memory is in and by itself no reason for concern; VM is not RAM, and the amount is insignificant. Moreover, unless you were looking at the actual PageIn and PageOuts, Activity Monitor only lists the maximum amount of VM an app can access, not what it actually uses.PS2, your question about what you shouldn't see in Activity Monitor is hard to answer, but excessive CPU loads and RAM usage might qualify, to name a couple.
