Playing against bad players

Why is it whenever i play against a low level player, i always seem to play worse?

Maybe you aren't focusing enough, because you underestimate them. Happens to me all the time.

I used to have this problem, and diagnosed it as such:

I would not give my lower rated opponents' moves and ideas as much benefit of the doubt, and play inaccurate moves in response. The cure is to remember that one player cannot claim an advantage until the other makes a mistake, so play as solidly as possible (taking as little risk/complication as possible) until your opponent makes a mistake. Note: play SOLIDLY, not passively.

There's an old saying that good swordsmen don't fear other good swordsmen, they fear the rookies....and it's true, lol!  You never know what they'll pull.  xAsnl is absolutely right: play as solidly as possible and don't underestimate your opponent.

True, i mean really the only time frame i really play for real on is the 30|0. The blitz i do for fun, and generally the 10 min games i do just to try out a new opening i'm studying. However, when i am against someone a lower rating then what i generally play at, all of the sudden its like i cant find any good moves and i make mistakes left and right on the board.