The left one is pretty nasty only when using the old 1980s friction pins, which won't bother coming off even when pushed from behind with a Technic axle. No wonder they got replaced with a more user-friendly type of friction pin.
The right one is quite simple, 1x1 plate on 1x1 round plate, the Brick Separator won't work well on this kind of combination and you will definitely hurt your fingers/nails in the process!
Ok so those two are not that bad, I'm sure you've seen much worse! What are some of your dreaded unbreakable assemblies? And do you have any good tips for taking them apart?
Edited by space6901, 04 March 2010 - 04:23 PM.