My wife and I are social nudists at a resort. We have friends there that my wife is comfortable hanging out with; and as they might have certainly seen her naked bending over, on all fours, standing or lounging legs open, squatting, up close, etc...; there certainly is a possibility that it made enough of an impression that it was thought of later on while rubbing one out. And I'm sure that our male friends are also aware of that possibility; especially the husbands with the more "uninhibited wives." Sitting there legs open while socializing is certainly going to make an impression on most dudes. The "visual" of seeing some wives' shaven pussy up close has stayed with me; even years later.
Some would probably enjoy knowing this for a fact. Others figure as much, accept the possibility; but prefer not knowing.
But it would be naive to think it's just men. I'm sure some women have been so impressed by someone's husband's dick that it made an "impression." Women are usually going to be more discreet about rubbing one out while thinking about some other dude's dick. I'm not going to flatter myself; but the way I've seen some wives look at my dick...has made me wonder. Knowing my wife; if she knew, I think it would actually make her laugh...