Well, speaking as someone who DID have a picture that was ruined (not by flashers but by someone in the log doing something they shouldn't) and who did NOT have the option to redo that picture it was quite disappointing. Our son spent all week building up the courage to even THINK about riding and then all day working up the courage to atually ride. We went through the queue 3 different times that day before he decided to ride but all 3 times he chickened out so he and I stepped straight through the log and left to watch DH and our other DS come down the drop outside. The 4th try he FINALLY rode and one of the things that motivated him to do it was seeing that he could get a picture of himself to show Grammy and Poppy. That was to be our last ride of the evening and of the trip as it was the day our APs expired. It was even more disappointing that it got through the original picture censors since it wasn't something obvious like someone flashing so DS SAW the pic, we ordered and paid for it and THEN were told no, we couldn't have it. My son was really upset. He was tired and had been SO excited about that picture. I BEGGED the CM to let us have it and the manager said they would be more likely to let us have a "flash" picture because it is just in poor taste but not something someone could sue Disney for and use the pic as evidence which they thought this photo could be even though it wasn't our family doing somethng wrong and the woman who did was long gone, we didn't know her (but I guess they can't know that for sure). My son cried from Splash Mountain untill we got back to the RV at Ft Wilderness and started getting ready for bed. Even an ice cream wasn't calming him down. If this had happened earlier we would have been fine because even if we couldn't have gone again, he wouldn't have been as tired (he had taken a 4 hour nap that day but it was still 11 PM on the last day of a week long trip).
Bottom line...it really soured the end of our trip. I am not mad at the CM or at the lady who pulled her child into her lap b/c I know how upset the little girl was and being a Mom too I understand wanting to do what you need to to comfort your child. I was just really disappointed in the situation. To be honest it would have been better if someone had flashed and the picture never even came up on the screen, as it was he could SEE the picture both on the screen and in the CMs hands and a preschooler doesn't understand "you were fine but this lady..."
Was it once in a lifetime...well, yes and no. It was the first time my big chicken of a DS rode a "big boy ride" so in that sense, yes but we have ridden Splash (and bought the photo) again since. Did it ruin our trip? No, we still had a great time overall but it sure didn't end on the high note it would have if he'd have left with his picture to proudly show off his bravery.
He still talks about how he can't have a picture of his first ride on Splash Mountain and how mad that made him. The fact is that THAT particular photo was special to my child for a reason and because of something
someone else did, he couldn't have his picture. No, I don't think my child is more important that anyone else (he is to me but his rights aren't more important than anyone elses). The point is, the people who are doing something they aren't supposed to can't know if their "fun" is ruining things for another family that this family doesn't have a chance to "redo." Personally, even as a teenage girl, I could find other ways of having fun than flashing the camera on a ride! How much "fun" will it be if they are caught and thrown out of the park? Hardly worth it, IMHO.
All that aside, I don't think the OP has to worry about flashers...it's not a common thing, 99% of the time your picture will be fine. If it is washed away you can't know for sure why....could be a flasher, could be a rude hand gesture or it could just be a technical error and the camera didn't fire correctly.
Sorry but some people get bent out of shape over nothing. 
). People "having fun" can't know if the strangers in their log have someone with them who don't see it as "just" a picture either. 
I would also bet that more often than not when it says the pic was washed away it was for something other than flashers. Something like technical errors rather than "rider errors." 
