On average, my ideal would be about two or three times a day, although I saw a story once called six times a day that I found fascinating. I'd love to go that often if I had the time and the stamina and willing partners, but with that being an average instead of a maximum in a given day, I think that would wear me out pretty quick. Once or twice a day would be more than enough for an average. Three to five times a week would be a good minimum average though which I'd be okay with if it was the best I could get. I could settle for that.
I'd say its a major turn off, because first off, it isn't natural flesh, and secondly it comes of a vain sense of insecurity that shows a person feels the need to have something artificially added to thier body to feel beautiful, and I'm not into that.
First time I tried it was because a woman I was getting passionate with, told me to stick it in her ass. I didn't argue. A few years later a girlfriend I'd been with for a year by then said they had never tried anal and wanted me to teach her about it, so I did, and she loved it, but only did it when she was in the mood.