I hate people on servers that say you suck at PVP then when you kill them they cry about how they were lagging or some other lame excuse.
Then once you kill them again they find another excuse as to why they suck so hard at PVP.
(There are a lot of people like this on Mineplex, specifically Dominate and SG. i don't know about other servers)
Most if not all faction servers are full of players like this. And I've played Mineplex, and there are a TON of people who do this on Super Smash Mobs.