What has been your experience with Ticketmaster online?

Last year I bought some tickets on-line during a presale and when we got to the venue I noticed a lot of empty seats in front of me. I felt like I had been jipped. Tonight I went to a concert and there were rows and rows of unsold seats infront of me--some mighta been more expensive, but there is no way all of them were--all in all I paid $221.00 for 4 tickets!! I bought my tickets last November!! What the...? Well, the venue rep (I assume) came up to us poor folks sitting in the last two rows and said, "the seats up in so and so didn't get sold so you all can move up." Which we quickly did. I thought that was really cool of the venue lady. I think the tickets where we ended up were the same or maybe $20.00 more a piece--if they were then I guess we just got lucky. I am no longer planning any ticket purchases on-line. I'll wait to buy my tickets at the last frickin' minute from now on!!!