Technically, they are associated, though that link should diminish much more quickly than a piece of hair. In fact, the best way to handle it is to say that they found a leg hair (or whatever) in the pants, and that is the focus of the sympathetic link. If you don't want to establish stealing clothes = sympathetic link, but you want to reward them for their cleverness, retroactively place a forgotten item IN the pants which works as a more plausible sympathetic link, and explain that stealing clothes won't always be an immediate link.
Certainly rationale for wizard-savvy foes to always wear new clothes.
Also, scrying - in the D&D sense - has been established as a VERY hard thing to accomplish in the DresdenVerse. Harry needs Little Chicago, and that only works for Chicago.
That said, we had a similar scene in my game, except it was the bad guys who stole the good guys' clothes. Our werebear entrusted an apprentice wizard with his own, personal (non-rented) tuxedo, and later that scene, the wizard used The Sight and ended up being motivated to get the hell out of there, and accepted a Compel to drop the pants. The bad guys took the trousers hoping to use magic to find the players later.