They do look at over stays not just in thailand but in other countries as well. there is no telling how this will effect you. It probably won't but they do look at it.
no secrets i sent a 2 minute voice message on why I got an agent for my situation and especially when I was applying there were a lot of changes to the application and why it was way better to just get an agent. I just didn't want to type a mega message in here.