By dates, do you mean the person you're going on the date with, or the event itself?
I can honestly say I've never had a bad first date. I go in with a completely open mind, so I don't have a ton of expectations other than meeting someone new and potentially having a good time. I love meeting new people and getting to know someone--one of my strong points is that I can make anyone feel comfortable and have fun doing it. This, however, poses a problem when after the date (no judgments during!) I realize I don't want to see the guy again. He's thinking that we had a great time and he wants to do it again...and I'm like, "another great date! On to the next one." I guess it's like sorority rush that way, when you think you made a really good impression on the house, when the truth is they cut you while you were sleeping.
As far as actual guys, I didn't want to admit it but I have a type. Tall and slim, brunette, intelligent, college-educated, reasonably outgoing, and SANE.* I'm not attracted to short and/or overweight men. After having tried the online thing, I learned that a lot of men say they're 5'7" when they're like 5'3". I'm 5'5". If you have to lift your chin to kiss me goodnight, then you're not 5'7". I'm not asking for a guy who's 6'5", I'll save those for the tall girls. I just want someone who's 5'7" and over. I don't think that's too much to ask.
*That's also the basic description of my first serious boyfriend...I wonder if that's the imprint I took, because I no longer find him attractive.