Believe me, when you have the 'right' girl do it for you, you WILL definately know!
It's the same with all aspects of sex, some girls are, well, fucking shit at all of it to be honest, but when you find that 'special' one, FUCK ME, it's GREAT!!!
I've known a girl since school, erm, nearly 15years, and she just had a natural talent, just fantastic, I still see her now!
And as for too much porn affecting you, I think you are right.
I could not cum with my girlfriend for months, I thought something was wrong with me, maybe I was having problems 'downstairs'. I could get hard, but just couldn't cum with her, porn yes, her no!
Went to see my 'special friend' and her tongue worked its magic and within 5minutes she was swallowing my load!!
OK, doesn't say much for my girlfriend, but I've laid off the porn for a few weekes and things are much better, oh, and I still visit my 'friend' just to make sure...........