When I was a kid, I loved the idea of Transformers and GI Joe being in the same universe. However, I hated the idea of GI Joe interacting with aliens, superheroes, monsters, etc. For some reason, Transformers (one of the least believable types of aliens to be, if you really think about it) were just fine mixing in with the Joes, but not the Lunartix or other aliens.
I liked superheroes, but I did not want them existing alongside either my Joes or my Transformers. I had no problem with Serpentor existing and sort of accepted Cobra-La, but mutants, mummies, and other monsters were just right out.
I've loosened up some on that and allow for mixing now, where my only concern is scale and consistent/similar design amongst brands. In fact, in search to make sure I hadn't posted this thread before,
I came across this post I made a few years ago. That's still pretty much the backstory for my collection, making sense of the various lines I have any interest in.
So what illogical play habits did you have as a kid? If you're still a 'world builder' collector, what ones do you have now? Which ones have you eased up on or let go of?