How to look up your coach's rating? You need your coach's name. Go to
Enter your coach's last name and first name, for example (me):
There might be couple of them. Choose the right state. Usually that will be the correct one.
This is the way to find out your coach's rating, in fact, anyone's rating. My rule of thumb is: your coach's rating should be 500 above your child's rating. That's why 1500 is the graduation level under my teaching. It's not that I can't guide anyone above 1500, but rather the student could gain more from an IM/GM coach at that level.
If your coach doesn't have any rating history in USCF, either he/she has retired from chess long time ago, and no longer playing in tournaments, or he/she never had a chance playing in US. You have to evaluate him/her by his students' performance and other parents' recommendations.
If your coach is outside US, you could look up his/her FIDE rating too.
Rating is not everything. Coaching also includes teaching style, curriculum, chemistry with your child, responsiveness outside the class, and whether he/she cares about your child. But rating is an important hard number no one can fake.