I think Maya made some good points, except I do think cats (at least some of them) possess a fair amount of intelligence, although some seem to be somewhat lacking in that area (not mine, of course!)
Found this interesting link regarding intelligence of cats:
http://www.messybeast.com/intelligence.htm
Yes, I agree about the sauerkraut, amazing they would eat that! maybe they liked the saltiness? Were they ok after that? Also, my Annie cat is quite destructive (and also seems hungry all the time). Could just be me, but she seems to do destructive things just to get my attention. But if yours are doing this when home alone, that would not be it.