I look at this as a game theory problem. If the number of VC's out there is very large, they are not well-connected, and the number of funding interactions you

I look at this as a game theory problem. If the number of VC's out there is very large, they are not well-connected, and the number of funding interactions you're going to have over your career is small, then ask away. Who cares if you upset that person? You're never going to deal with them (or their network) again. If, on the other hand, the number of VC's is limited, they are well-connected to each other, and you plan to ask for funding repeatedly, then how you handle each individual interaction becomes VERY important, because it has a high chance of affecting all of your future interactions. I find that much of the advice out there on sales and networking is focused on the former case, where the goal is to maximize the chance of a win in the first contact, even at the risk of making an enemy.