There probably are some support groups in Cincinnati. You could probably find them with a simple Google search.
Most groups in my local area are open to allies. But the degree of openness varies from warm welcome to barely tolerated. Someone who comes in talking about "ordinary" men as opposed to transmen would need to learn very quickly about how to talk about trans* identities in a way that does not alienate and disrespect the attendees otherwise they would find themselves unwelcome fairly quickly. Those who want to meet trans* people for erotic reasons or who fetishize trans* people would probably find themselves immediately unwelcome. My guess is that you'd find something similar to that in Cincinnati or other major metro areas.
I would second the opinion that you should do some homework before approaching the trans* community. The fairly blunt truth is that it is not every trans* persons job to educate every curious non-trans* person. It's your job to do it yourself. I also agree that you should think about your motives. If you are a person with a genuine desire to offer support and understanding, then such people should always be welcome. But if you are just curious, then that curiosity may be better satisfied in some other way. If, by chance, it is a desire to find a sexual hookup or something like that, then it would probably be best to stay away. Find somewhere else with trans* people who are also looking for that if that is your interest.
