Some tricks, such as bowing, yeah, cute, harmless.
But it makes me cringe and want to give the kid a giant lecture when I see them teaching horses to paw the ground, rear, kiss etc. So, so SO dangerous. This is NOT a cool party trick. Rearing in particular. If you want the horse to stand up, flip over and kill you - by all means, go right agead. VERY cool trick that, how about sitting in hospital in a coma, living life as a vegetable or spending it in a wheel chair unable to move your arms and legs... what a cool trick!!!
Pawing the ground, seemingly harmless at the time. You ever been on the receiving end of a strike? No? How do you like a broken leg? Or if you're lucky a whopping great bruise or laceration requiring multiple stitches. Again, very cool trick, you'll get some good photo's of your ruined leg for facebook, COOL!!
Kissing - oh gee, how cute :) Your kyoot poneee gives you 'kisses' on the cheek.... how about when cute pony wants a treat NOW and gives you a good chomp? A friend of mine lost his entire bottom lip when his 'kyoot' 17hh warmblood stallion wanted the carrot in his pocket, and went through his list of tricks to get it without being asked. Kiss turned into a really cute 'love bite'. Want a horse hicky? Teach him how to kiss - sure you might lose a lip, nose or cheek, but how cute, and hey, MORE really cool facebook photos to show off.
What more could you want? How cute :)