Does one have to clean all their dirty clothes before Pesach (on the principle of being careful to washout all the chametz from their house)? What is the general Halakha for your clothing collections (including your clean clothes) as it relates to removing Chametz before Passover?
According to Shulchan Aruch Harav, you should check your pockets, especially if you sometimes put chametz in them:
Every person should be careful to check and shake out his gloves and clothes-pockets, and those of [his] children, because at times chametz is [placed] in them... All the above [applies with regard] to one who is wont at times to [place] chametz in his gloves and clothes-pockets... Nevertheless, may blessings be bestowed upon one who is stringent [and searches these places (regardless)].
This article says that freshly laundered clothes don't have to be checked, as any chametz in them would have been destroyed.
Clothes worn on Erev Pesach should be checked or washed after you're done eating chametz.