I love long hair on a guy but it has to be more modern like emo/punk or if it's really long, mostly straight/slightly wavy and in a pony tail. But if he's cute, it doesn't even matter. Adam Lambert has short hair and its awesome!
I like a man's hair, no matter what length,to be clean. I like men who are bald or going bald without combovers (it just looks ridiculous). I like running my hands through a man's hair or over his bald pate - so sexy. And long haired guys - it's sooo sexy for you to drag your hair over my breasts. Any of these with a mustache and/or goatee is even better!
I tend to like guys with longer hair with natural wave. Never tried bald since I like to run my fingers through my guy's hair, but wouldn't rule it out. Look at Yul Brynner. There has never been a sexier man alive than he was.