I think the purpose of this thread is for pointing out people who are accidently in your photos, not photos people set out to purposefully ruin. Flame me if you will, but I'm exercising my right to speak up.
I have an issue with someone deliberately "bomb"ing another family's photo ops. We had staked out our spot at Epcot for Illuminations a good 90 minutes before the show started, and my daughter had set up her camera on the tripod so as to catch photos of us during the show. We had been there long enough to recognize other families around us. When the show was over, the 14-year-old daughter of a group near us decided she should jump in front of our camera set-up and make faces into the lens when the timer was set. The ignorant klutz's big feet got tangled in the tripod's leg and caused the tripod to topple over. Thank God my daughter had cat-like reflexes and the mindset to jump up and catch her camera within INCHES of it hitting the concrete (then again, it cost her over $500 and she guards it with her life). The parents watched it happen, and yet there was no apology. They gasped and hissed at her to "get over here!" Yeah, reallllllllllll funny.
As far as ride photos go, I think if you're the only family in the ride vehicle and no other families' photos will be bombed by your playfulness, then, by all mean, bombs away! However, if there are others with you, I would hope for some consideration. Given the long wait times for rides, some families may not plan to ride an attraction a second time. I'd hate to be the reason they wouldn't buy a photo memory of the vacation they've planned and paid for.
G'head, let the flames ignite.