I lucked out that the the first A/B/O I read was freakin' amazing. That kind of gave me the fortitude to make it through some of the squicksome or poorly written ones.
Some of the A/B/O is really *out there*, but I have seen a few that are much more subtle. Alot of personal identity vs. psychosocial expectations vs biological imperative issues. And of course the hot sex and warm-fluffy-soul-bondy-stuff is nice too.