I do think that many touchy topics have already turned ugly in the past. Then another DISer starts that topic up again, often worded in a way that may raise hackles right off the bat. I have rarely (never??) seen an innocent question, with non-insulting wording, get attacked right off the bat.
That was my long answer.
My short answer is: I think there are some sore subjects. Anything questioning another's parenting, socio-economic status, upbringing, religious beliefs, or political leanings need to be brought up with care, and discussed with even more care. What I have seen a bit of very recently is topics that, right in the OP, are started off on the wrong foot. I have also seen quite a few new threads where OPs specifically asked for opinions, yet felt attacked by any and all posters who disagreed or failed to validate.
The fact is, this IS a message board. There are people on here from all kinds of backgrounds, with all sorts of values and beliefs. Gotta have a thick skin before starting threads that might flare out of control.