Well, a few things --
Do people compliment you on your appearance?
Will random girls smile at you on the street etc after brief eye contact?
A few years back this started to happen for me pretty often, but I was too stupid to take advantage of it. Now, it's all good
And I don't see it as 'taking advantage' of women. Many of them aren't necessarily interested in long term things either. As long as you're honest about it I don't see a problem with sleeping around.
I know this one guy who is far from a winner in the looks department, but is always dating very attractive women. Sure some won't go for him, but others will. I think a lot of it is exuding self confidence, and taking chances. The fact that you are getting a lot of 'mixed signals' suggests to me that your prospects are a lot rosier than you might think.