Biiig nay. Look at me I'm a horsie, NAAAAAY.
I had someone recently shoehorn their comic into a comment a little while ago. It was like, "Oh wow, I love this comic, it's great you should check out my comic here" and I was just like rolls eyes and ignores
Whether you do it blatantly or you shoehorn it in one way or another, just don't do it. You can promote your comic in many other ways that isn't personally chasing after people begging for them to read your stuff. It's embarrassing for everyone, yourself (as the creator who's advertising) included. It just screams "I'M NOT CONFIDENT ENOUGH AND TOO LAZY TO MAKE MY COMIC GOOD WITH MY OWN HARD WORK LIKE EVERYONE ELSE HERE". Complete desperation at that point.
It's spam, plain and simple. Ignoring the first one is easy to do, but if it's repeated attempts, then you're just invading someone's space with unnecessary emails/posts/PM's, etc.