Based on my experiences with the women I have known. I doubt a variation between “No” and “oh god this is great” can be safely established with men.
In my personal experience, as well as from whatever I’ve ever read, this is not a real issue. The sphincter can be relaxed through stimulation, but barring any actual muscular damage, will go back to its natural puckered state pretty quickly. Even then, a relaxed sphincter is not the same as a loose one. In fact, to be a bit disgustingly frank, penis sized objects tend to pass through there on a regular basis.
The only people I’ve heard pushing that argument are those who refrain from anal sex for that exact reason.
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I’d always heard that a big part of the pleasure men get from receptive anal sex, is through prostate stimulation. Women lacking a prostate would lack this.
Though since the bowel and vagina are next to each other, it’s not unheard of for some women to get g-spot stimulation anally.
For the love of all things good, please NEVER link to such a study.
I seriously wish I knew how to make a pair of ascii-fists. With a ring on one finger.