I pass a race when I don't see a reasonable way to make money wagering on the race. Typically this is when my vision of the race is just like the public vision. A race where my choices could win but still not yield a reasonable profit. I should note that I may still include these races on horizontal wagers.
Another type of race could be when there a too many unknown factors. For example, there may be larger number of FTS. Once again this race could still be included in my horizontal wagers.

@Tony Kofalt
Agree Tony! Knowing when to pass is as important as knowing when to play!

Handicapping Wise
1) Straight maiden races with 0 starts for all starters (obviously, lol)
2) Some maiden horses have started, but 2+ horses are FTS
3) Races where starters have 0 Beyers/BRIS figures but have starts
4) multiple foreign horses in races (excludes Breeders Cup)
5) smaller fields= no honest value (in a way for me)

Betting Wise
1) Races where the favourite will drown the value down of the race (1/9 shot= no value race etc.)
2) Where my top pick has a lower % chance of winning
3) Where my exotic horses have a lower % chance of winning/hitting the ticket

4) multiple foreign horses in races (excludes Breeders Cup) — Conley

Do you define "foreign'' as having only foreign races showing or would it include any horse with any foreign races showing? For example, if a horse has one North America race showing and the rest are foreign, would you consider it a "foreign" horse?

I would define it as:
Horses who have only foreign races showing. Like all starts in UK, Ireland, Japan, etc then shipping into todays race. And still if he has 1 NA race and then goes back to his/her homeland I would still consider that horse foreign.

Everyone, do you pass on wet tracks?

I pretty much pass nothing. LOL

I play races differently, but I believe there is always a way to leverage a bet out of a race.

Must admit, that this position is getting tougher to maintain.

Ranch, I do not pass on wet tracks. But as someone who plays primarily horizontal wagers, I find more fields scratch down on these surfaces. I have to be careful with the prospect of short fields.

@RanchWest,
I rarely pass wet track races simply because of the wet unless they're on wet turf and don't get taken off .