rigamagician: thanks for those games. I've never played the Ruy where someone accepted the pawn and everything i've read says it's bad. Losing by force though? That is provocative. Is this true?
Fiveofswords: You make a good point. Is it really a gambit? I would think that any gambit is based on the theory that you are getting something for your sacrifice. Frankly, any move you make should offer you something, better position, active pieces, mating net, etc. I don't think the Ruy strays from this line of thought. I was just trying to point out, that while taking the pawn is rare, it is still a good example the soundness of offering material under the right circumstances. It just seems that nobody calle the Ruy a gambit line because nobody accepts it. Which takes us back to your point. Is it a gambit if it is never accepted? I'll leave this to the experts :-)
I think that there are some differences between playing a gambit that you have analyzed at home and know the ins and outs of versus a sac that you come up with at the board in the heat of the moment. On the other hand, though, both serve to spice up the game, and the same kinds of players are likely to be attracted to both. Perhaps some types of players are more likely to be attracted to speculative sacrifices for the attack, while others prefer long-term positional compensation, but I do think a lot of gambiteers seem willing to play both.
I understand though the distinction Benkobaby is trying to make. The Benko gambit in particular saddles white with pawns that are hard to defend, and this can last on into the endgame, and thus casts a pall over white's whole game. It would be nice though if you could come up with that kind of long term sac in middlegame positions as well, but that isn't always the case. Petrosian and Botvinnik's exchange sacrifices are maybe of that type.