They might be alts, which according to the forum rules is allowed. So, I don't think any DT member may tag the accounts on grounds that they are just alt accounts posting in gambling section or exchanging merits {at least in the past, accounts engaged in merit abuse have not been tagged}
But if you have any good proof showing that they for example cheated in signature campaigns, contests, involved in trust manipulations etc., Now might be the right time to add that.