I pick and choose which trailers I play. If it is a film that I absolutely know we are not going to play, I don't use it. And I have always been careful about what trailers I play on G rated films. Partly because, like you, I've had complaints about unsuitable trailers, but mainly because I feel a certain responsibility.
You can always tell when the film companines think a film is going to big because you are bombarded with trailers. For example, last week with both Proof of Life and Vertical Limit, we were requested to play 8 or 9 trailers. My limit on any film is 5, since I usually don't have enough time
between shows for more, plus I think too many tends to irritate people and they lose their effect. Anyway, I feel like its my theater and I should have some control. The film companies can't control everything. It's bad enough when they make you hold films that are playing to empty auditoriums.