re: Question about ordering drinks and bartending

I see this poster is TigahRag...

His point is that you drank it so you should pay for it.
I would make this analogy.
If I ordered a shrimp pasta at a restaurant and ate all of it and said it was great and now I'd like my check. If the waiter brought my check to me and I saw I had been charged double that amount because the chef threw in double the amount of shrimp then I'd laugh in his face. I have no idea how many shrimp are supposed to come in that pasta and I just ordered the pasta, not a double serving of shrimp.

At a bar, if I asked for a single and it seemed strong I'd just assume the bartender had a heavy hand. I would have no reason to assume that I was getting charged for a double when I ordered a single.