Bethesda's bugs are fairly legendary. I remember Oblivion was incredibly annoying in terms of its frequent crashing, partly due to some bizarre decisions with its scripting language and lack of sanity checking, as well as very poor memory management that often caused corruption and crashing (a few people looked at the latter in detail and discovered it was really quite a serious mess). Some of the problems could be worked around, but it was frustrating.
My least favourite of their bugs is Fallout 3's "dead cell" bug which has been quite widely reported: a cell will at some point contain an invalid object that puts it off limits for the rest of the game unless you want an immediate CTD. It is fixable, usually caused by one of those "spaghettified" corpses whose coordinates end up out of range, so disabling the offending ID will fix the problem, but it can be a laborious task to find it and there's nothing to stop another one causing the same problem. It gets progressively worse with longer playing times, so it's probably tied in with a similar memory bug to Oblivion's, if not the same one. Of course being an identifiable and repeatable problem with a specific solution never stopped the usual culprits claiming "its your PC lol". <_<
And then there's bug-ridden DRM, which is the most annoying of all since it adds no value to the player. Steam's "preparing to launch" hang is quite annoying, but I'm really looking at Origin here, with assorted configuration problems, nasty EULAs and so on: in fact my experiences playing the latest DKS and then trying to get Kingdoms of Amalur to launch couldn't be more different in that DKS just did what it was supposed to whereas I had quite a fight on my hands to get KoA to start up. Why can't other games companies be like Larian?
