Possible reasons:

1) Your account is new. Reddit filters new accounts and we have our spam settings turned up. If it this happens, we (mods) usually see them fairly quickly and will 'approve' them when we do. This spam setting only lasts for a few days.

2) You're a guy replying to a 4MF or 4F ad. If you are complementing, that's fine, however, if you are "offering your services" or replying with "DM me" or "hmu", etc., those get deleted when reported or we see them. Someone is out there reporting almost every one of these so don't waste your time, guys. We have been asked to start banning guys that do this and we'd rather not, we'd like for the single guys here to respect others (maybe we're too hopeful on this??). We may start commenting that these were removed but there's a lot and we're just volunteers here. So GUYS pay attention to those Post Flairs and check out r/OregonMenGoneWild - Couples and single women use that sub.

3) Your comment Karma is low. Again, spam filters remove these but also, if you're a dick and get downvoted enough that you have low/negative Karma, do we really want you here?

If your comment was removed and you'd like it restored, review the post flair, then contact the mod team.