Yeah. Like, if you're promoting in places where they encourage promoting, I don't see why it'd be a bad thing.
It's just the way of self-promoting. You advertise your talents given the opportunities that arise.
Personal Social Media? You can promote your work there XD
Forums and Sites that want Self-Promotion? That's your ticket.
I think it's all about how you do it. Like previously said, it's more annoying if someone slips into your DMs, a total stranger, and self-promotes their comic. You don't know them, don't know who they are, didn't even get a simple "hello" -- they just randomly decided to PM you with this. That's where you can go wrong.
Long as you're not doing that, you're chill.