I'm a little curious as to why anyone that has their kids in a public school would care about whether their child was given a DIBELS or any other test. If it is like my state the results are not shared with the kids unless the parent wants to show it to them.
So beyond it being a waste of time and a foolish way to judge the quality of a school or teachers - what difference does it make?
It's been my experience in teaching middle school that HG+ children often know that the scores don't matter to them. So they have a tendency to mess with the test :-) I had one very brilliant student who made a beautiful smiley face with her scantron. Others just refuse to be bothered year after year. Having those scores sitting in your file can be problematic.
That being said, in our district, they will run you down if you try to get your child out of testing and they are above grade-level. The district will do anything for one more point in the average. I've known them to send home/hospital teachers to people's houses to drag STAR testing scores out of the kids who stayed home "sick." It's just not worth the fight as a parent. As a teacher, I prefer bribery. Do your best, try hard and I'll buy ice cream!