Are we just assuming that neither Crowley nor Aziraphale has ever "kissed" anyone?

Hear me out, let's have a think about this... I understand that they are otherworldly beings of either heaven or hell. However, they have been on this planet "a long time", they've seemingly observed human behaviour, affection included, for centuries. They knew that "one good kiss" is "all it took" to spark love when it came to Maggie and Nina. Shax had said twice in the car (S2,Ep4) that she was "bemused as to why Crowley should risk destruction for you. You don't seem his type at all." And secondly, "...sometime in the last 80, 90 years I remember hearing that you and Crowley were an item." All of this to portend that they understand meaning of physical and emotional affection, as it were. All this being said because I've seen a lot of chatter that poor old Crowley in one last desperate attempt to prove and show his love to Aziraphale, was, by a crudely executed human gesture (a desperate kiss). As in to say, he didn't really understand what he was doing, he just tried it as a last ditch effort. However, I think there is a great deal of previous evidence that they do understand this type of interaction, love, tenderness, affection, and quite simply, touch. All that being said, and in addition to past comments, do we think that for the last thousands of years, neither one of them has EVER engaged in any sort of relations, physical or otherwise? (And not just with each other, but anyone, really.) (Mine is all sorts of speculation and theory... I'm not married to any particular idea, so I am open to any/all, and hope I don't get lambasted for theorizing or wondering.)