You can report a few of their posts, and include a message in the report field that they have multiple bad posts. If it isn't obvious then you could just report all of the messages you consider low value posts. However, if you are asking what will happen to user with low value posts being that of the majority of their posts then that depends on the moderator dealing with the user. If they deem it bad then they may request a global moderator/admin to ban the user. Really depends case by case.
I have seen a lot of users having that type of issue and it's mostly because on the topic they are posting it too. Maybe it has been answered already or they just keep repeating it over and over again. I'm not saying it's bad but once you post on the same topic and repeat your opinion again, I think it can be thought of something bad in my opinion. Not knowing that you have posted in it already and just because you want to add more posts to your account or something.
I guess it cannot be totally avoided but seeing stuff consistenly like that should be reported, especially if it's a low valued post.