I've often prided myself w/ my ability to decipher the vane plates.
In this case, I just looked at your Thumbnail and was a bit stumped on why somebody would put "Oh, Piece of Sht" on their car, unless they REALLY didn't like the car. A shame in this case considering the car.
I read down in the threads and got confused on the bloodtype thing, so then opened the file to see the blood donor portion of the plate at the bottom.
Unless cars will be right on your tail, I'd tend to think that most would read as I originally did -- from afar, and not get the blood relation.
Perhaps an "O-PLUS" would've been less ambigious (how often do you really see blood types written w/ the words negative or positive?? i'd presume even in your field it would be the sign).
Me too, not a fan, AT ALL, of the vane plates, but if I did, I'd spend an awful lot of time thinking, pondering, and considering every possible perception of the type i had chosen to assure the least amount of confusion, unless, of course, that was what you were after.
Clearly too late, but... well... ok then... enjoy.