can't believe that the guy you bought the table from said only 10% of records you'll buy will sound good. god, what a jerk! ok, so here goes...do everything everyone else here has already suggested. clean them records good...find out how. either here or audio asylum...means either buying a good cleaning maching(my recommendation) or using the disc doctor system. anything less than these suggestions and you've got challenges. also, make sure that your stylus is clean. get a good cleaner for that. either extremephono stylus cleaner, disc doctor, or last. all kinds of junk can get on it, even after you clean the records reallyh well. make sure everyting is level. get a bubble level from any hardware store. and yeah, make sure that the cart is in right, aligned, tracking force and tracking angle are good. again, check in at audioasylum.com, go the vinyl area, do some searches, and you'll learn a lot. you have a very good table. assuming the cart is good, it is capable of great things. i own the mmf-7, the next one up, and love it madly. if you want to put up with the inital roadwork, you'll be rewarded. if not, there's always the digital solution.
good luck!