i have first hand experiance of the police and customs tugging me for a check and a dip, the bastards were near a car auction i was going past and i was in a hurry going somewhere so i did a crafty u turn and thought they didn't see me, next thing i know i'm the subject of a apb and on the run in their eyes,anyway i get stopped and asked quite politely to return just for a dip check which i agreed to do, soon as i get their the fucker pisses off and leaves me with a thicko from customs and a copper i wouldn't of pissed on if he self combusted in front of me. they checked everything twice and kept commenting that the tax was up in 2 days like i was lucky or somthing, i pointed out what the first copper said and i got the verbal shit spouted at me. the customs looked at my diesel and it was a really bright green and the old bill was asking more questions like can we do me,i said if it aint red theres no problem then.
so then the copper gave me a producer and says i'm lucky

a mate of mine who got done for smoking red got a 500 quid fine and if not paid there and then the car was going to get lifted. he paid up and after a load of questions and a producer got told to clear off.

about red being smokey is a myth imo, a mate who runs brand new tractors that cost 60 grand plus vat uses it all the time and it doesn't fuck them up or sound or look any differant to normal derv.