This report has a very small sample size (five), but it suggests that men circumcised as adults report significant decreases in sexual pleasure.
Update: This study (via) shows a very subtle difference, and not all in one direction:
Category scores for responders with the same sexual partner before and after circumcision (30 men):
Erectile function 12.311.1
Penile sensitivity 10.19.4
Sexual activity 9.810.1
Satisfaction 11.212.3
So function and sensitivity are both slightly down, but general satisfaction and activity are both up.
Of the responders 47% reported that sex was physically more pleasurable and 47% also said that their sex lives were more satisfying after circumcision. Additional comments included improved penis cleanliness and easier voiding after circumcision. When asked generally about benefits and harms, 50% reported a perceived benefit or improvement, and 38% reported a perceived problem or difficulty as a result of the procedure. Overall, 62% of men were satisfied with having been circumcised.
Plus: "In a survey of college women 87% expressed preference for pictures of circumcised over uncircumcised penises."
Take that, Sanchez.
