Can teasing be subtle bullying?

yes. they should be called out on it! you maybe able to laugh first few times then....bite back....teasing is what you may do to a child not an adult! not that it's right for a child either.

Could these people be passive aggresive? I loathe people like that, they are harder to call out, and if you do they are hurt and offended, and they play the victim.
My friend and I used to tease each other, but it was just banter and we enjoyed it. I would not do it to someone I did not know well as it could cause offence. I also find some of these people sly, they can give it, but cant take it.

I was teased by my ex husband and it definitely was bullying. A joke is only funny when both sides find it so.

I have a very simple way of dealing with inappropriate comments, sarcasm or jokes at my expense which I learned having the sort of brain that took a few extra years to understand that sort of thing.

Now I just say I dont understand what they mean and make them explain till they feel awkward and go away..

It works perfectly for something discovered by accident