Any car parked with lights on, even sidelights.
Modern digital cams photograph very well with minimal light
Any car with more than one male inside.
We've all seen them, but times have changed and they're now more likely to be press or law than two mates out for some fun
A couple trying to arrange a meet, with the woman "working" and not available to chat.
The old ones are still the best, and that one has to be older than me
Any car with loads of yobs in
It's what they make firearms for
Parked cars flashing their lights, and being ignored by the others.
Do the same
Drunk, or drugged, women. With the bloke saying she wants loads of cock.
If she wanted it that much she wouldn't be drunk or on drugs. Remember: Wisley.
If you're gay, the blond adonis heading for the trees with a smile and a mince.
His mates are probably there waiting. The ugly prat in the micra is a safer bet, the other probably has a nice bed waiting for you: Hospital.
When the police talk to you, and ask why you're there.
You've had an argument with the wife (married)
You're waiting for someone (if it's a gay site, adopt a higher tone of voice)
You were driving and suddenly felt tired, so followed police advice (not if the site is at the end of a long dead-end road)
When you get followed by the inevitable shit-breath.
Drive straight home so the prat knows where you live or:
Drive to a pub, have a drink and a meal, then leave the car and take a taxi or:
Drive down a narrow road, get slower and slower, when the tosser gets REAL close BRAKE LIKE F*CK, then drive home
Any more suggestions