The [contest-math] tag was added to many questions recently, even old inactive ones, because a certain user "knows they look like a contest question" (math.stackexchange.com/questions/1274242/…). Does that make sense, even if the original poster does not mention a math contest or competition?

@MartinR I am not sure whether there are some users who still follow that room, but I have copied your comment also to Tagging chatroom (it seem relevant to that room's topic: chat.stackexchange.com/transcript/3740/2016/12/28 I have also added some links to related discussions, but I was not really able to find much past discussions related to (contest-math) tag.

@MartinSleziak Thanks, I did not know that room before.

@MartinR Well, other than quid in some recent discussions (related to countability-axioms, maxima-minima and some other tags) I usually only talked to myself in that room for some time. But, if nothing else, that room can at least sometime help to find past discussions related to a specific tag.

@MartinR (Un)Common sense tells me that if there was no indication on the question that it was a problem of known provenance, one would not try to guess the aspersions of the OP by adding contest-math on his/her behalf. (This is similar to the policy back when the homework tag existed.)