I did a couple of posts on the 'attacked' thread. But here is my full crackpot theory, born of personal experience, conversations with cops, and a fading memory of a RW story on the subject back in the late 70's or early 80's. Once again, I seem to be a magnat for harrasment so I have given this some thought. By the way I am a 42 y/o male and have been running since age 13, ran for HS and college teams, grew up in central KY; have lived also in AZ, GA, and now FL since June.
Personal experience (and many many stories exchanged with running buddies)
1. Faster runners catch more crap; then again we run more so the opportunity to catch crap is increased.
2. Regular length running shorts catch more crap (no not that kind of crap)than basketball "knickers"; this has come about only since long baggy shorts came into style - not a problem for me or mine prior to about the mid '90s
3. Males running shirtless catch more crap
4. Lone runners catch more crap, though my college team often got yelled at - but offenders tended to back down quickly from 15 guys.
5. Runners in and around Lexington, KY catch more crap than anyplace else I have lived, by far - location matters; it ain't Boulder (rednecks are everywhere, but their ancestral homeland is the south, and they are bitter that it has not yet risen again; note - do not flip off pick-ups with rebel flag stickers on them)
6. Runners on the road catch more crap than runners on the sidewalk, but the later does not make you immune to crap
7. Running roads with little or no shoulder leads to more crap
8. Male runners have their sexual preferences questioned ("f**got!") while females are given the "hey baby, wanna ride in my car" treatment more often; addendum: (straight)male runners usually do not mind female drivers doing this to them; you'll have to ask the gay ones what they think of it
Now the cops' theory:
1. Crime of opportunity; there is no more dangerous vehicle on the road than one occupied by 4 male teens; the mob mentality takes over and they do things they would never do if alone
2. Jealousy; one cop managed to do a 'stake-out' to catch a driver that harrased several ladies every morning on their run; the driver - an overweight female nurse - confessed and said she did not like the girls 'showing off' and making her feel bad (as if that is why they were running)
Old Runners' World Theory:
They noted that you can of course only interview the ones that get caught, but they looked at police reports and what the perps said. Pretty much the jealousy theory was supported; the perps think that we runners are "showing off" and need to be taught a lesson. There is the vigilante aspect too, if I recall correctly, in that the drivers think it is illegal to run on the road so they are doing you a service by letting you know this (via blowing the horn, telling you to get off the road, or swerving at you).
Prevention: make sure you wear a gunny sack, don't ever run on the road, be fat and slow, and for god's sake tape your middle finger to your ring finger so you can only give that Hawaiian salute thing, bra!