So what I find interesting in this thread, which was a great topic idea, by the way, is the common thread, with the exception of the lever guns, all of the most hate, high maintenance problem children are semi automatics and primarily pistols.
I tend to avoid automatics as much as possible, and handguns in general. I do, however, own a Winchester Model 50, early 1950's production date, and I am scared poopless to even attempt a disassembly. It was my grandfathers and now mine. Earlier this year, I was going to take it apart for cleaning (probably never done), but, fortunately, I did some research ahead of time. After learning that the gun had to be TIMED (like, as in timing an engine) during reassembly, and, if done incorrectly it would cause failure to extract, fail to feed problems, I simply gave up the idea. From my research, the Model 50 is a very precarious machine, but, fortunately, doesn't require that level of disassembly/retiming but about every 10k rounds or so (which I don't think I will reach even in my lifetime or my son's)
I simply spray the hec out of with Birchwood Casey gun scruubber, although I'm thinking of switiching to brake cleaner as gun scrubber seems identical to brake cleaner, but brake cleaner is WAAAAAY cheaper.
PS: I also have a Marlin Model 60, which I have dsmantled probably over a 100 times or more. (So much so that I now have to use teflon tape to keep the screws from backing out during use.) I don't take apart the trigger or loading mechanism/group that sits under the bolt; I just take it out and scrub it good. I've never had an issue doing it, but it is time consuming, and I would much rather have a bolt action. It currently won't eject and won't feed, so now what I have is a very complex single shot. Go figure.
minutes, I think I spat more obscenities 
