I rarely complain about lag during games, sometimes I will since players like to pick levels that are easy to control in duels, thus they are very lag sensitive (If you don't believe me, try dueling a few times in DW and see how an airhit will screw you, even at 4-0 or 9-0). That's not to say that everyone is justified in saying that their defeat or win was caused by lag. There are lots of exceptions, such as lag giving you an advantage if you have some of it, since other players shots won't register on you etc. It's generally worse to have more lag though.