How do you graciously decline being set up on a date?

A coworker wants to set me up - Not sure I am really ready to date yet and I am really enjoying being single right now. The guy she wants to set me up with is nice and all (I have met him) but I like guys who are a little more rough around the edges - motorcycle guys, tattooed guys... This is a standard business looking metroual (almost) guy.... AH - I dated one of these last year and I just got bored because he kept turning my music down.