The mild hysteria reminds me of the "Satanic Panic" of the late 80's with no Geraldo to hype it to the Moon. We need Dr. Phil on this one fast.
As for the clowns themselves, it's a classic ladder conspiracy. Someone does it, gets some attention, other folks hear about it, think, "That sounds like it could be fun" and you're off to the races. The thing takes on a life of it's own after that, replicating like a virus as every nimrod with a clown suit gets in on the act.
It seems to have started in N.C. during the summer and moved up and down the I-95 corridor from Florida to Maine. Now it's making it's way across the country. I've got the feeling that there's a 16 year old in N.C. thinking "Oh ****! I just wanted to scare the piss out of my annoying lil' brother and his friends. What if this comes back to bite me in the ***?"
It kind of reminds me of something that happened in Point Pleasant in 1966.