surely if you need to ask and don't just know - from how they look, talk, react after - then you weren't that good or you're just very needy and after confirmation?
if we're both moaning and groaning and encouraging each other during, and after just laying there, panting, sweaty, covered in juices and smiling/saying 'wow', then i know we've both had good sex and enjoyed it, if my dick is 'sore' it means i've fucked my bf several times in a row so always a winner in my book , and if he cuddles me after smiling and looking happy then i know i've pleased him.