Well I only have had experience with a relatively small amount of horses so my experience might differ from other peoples experience, and well while there are some similarities in the textures and feel of an equine penis compared with a human penis the smells/tastes can't be any more different.
The horses I've played with ranged from dirty geldings to freshly cleaned breeding stallions and anything in between, some had skin flakes, some stallions cleaned naturally due frequent masturbation. In my personal experience their penis when is not clean but not very dirty smells very similar to their body smell just stronger, the base of their penis usually smells somewhat sweet like some kind of artificial flavoring reminiscent of synthetic strawberry flavoring with margarine with a leathery strong horse smell, those are common smells I can think of that come the closest to describe it but not exactly so don't think in a tasty smelling candy, I can't think in anything better to compare, ear wax also has some reminiscence but might be a disgusting comparison also it might smell different from each person. Anyway I love that smell so I will call it "good", such smell fades as you move from the sheath/base of their penis thorough the shaft and as you begin getting closer to the glans it starts smelling not so good, the urethral fossa usually smells bad unless freshly cleaned and had the "bean" removed, it smells like some kind of rotten lactic food, I cannot really describe that smell its not very butyric or cheesy just smells kinda like bad milk with rotten horse urine and some horse smell, not enjoyable at all so i will call it "bad", if their penis is extremely dirty the "bad" smell will be quite bad it might make you gag if you smell your hand after handling their glans, also if they sweat a lot (as in working hard daily in summer) the smell at the base of their penis turns into a very disagreeable smell too but its rare, out of all the horses only one suffered of this, however a very clean penis barely has any smell, it just smells like horse.
The smells changes depending on their diet and also the time of the year and the amount of exercise, if they sweat a lot and frequently their penis smells worse as i already described, I also noticed that when you suck them the smell changes the days afterwards unless they are keep very clean. You might say, "Im asking about taste not smells!" well it tastes like how it smells just stronger because its how tasting works, in your tongue you won't experience any significant flavor, its just like tasting very soft and smooth skin not sweet or even salty its all in the smells. Some horses are more smelly than others and some have a very strong "good" smell and others a very strong "bad" smell but most have a stronger "good" smell than "bad". You can even know they have an erection without looking if you are close and the air carries it to you (farthest Ive managed to know they had an erection due the smell is about 5 feet) because you immediately perceive that particular smell turn to look and you are greet with the view of a beautiful phallus freshly out of its protective sheath getting some fresh air, I love it.
The best way to experience some of those smells without doing something that can't be done in public is to get very close to the horse and put your face close to their flank (when you groom them is the perfect time) if there is no wind and ambient temp is not high the rising air due their body heat will carry some of that smell from their crotch upwards their flank and unto your face, so even if they don't have an erection but their penis is barely poking out of their sheath you might smell something.
Thanks for the nod, m'lady. <bows slightly>
