This is within reason.
There is two (main) scenarios:
1. You have a coach with a good reputation & well respected ... and, he doesn't have good things to say about you ... that's no bueno.
2. You have a clown show of a coaching staff ... and they don't have good things to say about you ... well, this is less no bueno.
The great thing about today -- word travels much faster, and circles have become much more intertwined in the baseball world. So, when you are a clown -- word travels fast.
In other words, if you have a clown-show coaching staff in high school -- and, the clown-show coaching staff says bad things about you -- it's taken lightly because of the reputation of the staff.
I am not advocating you to be a jerk because your coaching staff doesn't like you -- just show up -- do your job -- smile more -- worry less what your coach is telling others/scouts, and perform...everything else will take care of itself.