I can imagine it must be really annoying.
I guess it's the price you pay for a platform based on monetary gain.
Although that's the good thing about the upvote system as the bad comments will stay on the bottom of the post and the good comments will be at the top for everyone to see.
Usual the people who ask follow for fallow upvote self comments ....
I just noticed this on a few of my posts too, I did not even think one could do that. Great post @patelincho I totally agree as I have been receiving many spams lately as well. We have worked hard and still do to make good, informative content and still have some fun with our community here. I am glad you wrote about this, as new people need to see it only hurts themselves in the long run.
As soon they see this , so soon we will have better place here in Steemit for everyone :)