I've never actually smelled the stuff from my mare LOL but if some of you mean that you can smell it wafting up from the horse's private place without getting too close, then I got lucky as well, because I never notice a smell from Sandie at all!
Although I do clean her every week so maybe that's why?! It seems like that sticky nasty dirt stuff gets in there SO fast though! Man, I can't imagine the poor wild horses who don't have anyone to clean them!!