I had to put a rooster on a local classifieds site last night, and in my ad I said that he is free to a great home on the condition that he be kept alive. What I look for in people responding to my ad is people with decent punctuation, people that aren't demanding and someone willing to develop some type of rapport with you. Also, go with your gut.
I've had 2 responses already, and one of them was a HUGE red flag for me. The person said "hi good morning do you still have your rooster please I need him"....I didn't feel comfortable with that at all. You NEED him? For what?
The person who won me over was polite and willing to talk to me and explain why he wanted him. He has some hens in a nice coop with trees in it and the rooster would have a really nice life.
I think you just need to go with your gut. That's what I do. If you don't find someone right away, keep trying. Someone will eventually want to take a roo and give it a good home. I am a "crazy chicken lady" now, and I made sure the guy who wants him knew that I have expectations of him taking the rooster since I became attached to the little guy.
Hope this helps.