There are people who save up money and get one time off all year that take vacations to places like that. It would really suck if some jerkass ruined it for them. Pranking your friends is funny, pranking strangers is just being a dick.
I don't see how a bird crapping on you will ruin your vacation. There are plenty of showers available on the beach.
I would bet good money that none of those pictured are on a once a year vacation to some random Cali boardwalk. No way we'll ever find out, but going to Long Beach is like going to Galveston for us around here, just much nicer. We don't "save up all year" to go to Galveston. That said, I do agree that being the victim would suck. The baby shot is the best because, it didn't hurt the baby, the baby won't remember, and is hilarious, but wrong.
I laughed and wish I would have thought about it back when I had no cares. Would have gotten the father-rage now if my kid was shat upon and I knew it was a prank.