I don't work at a bank.
I live in reality. Reality is, that a collection agency has been seeking $31 from me since 1997 for a Sprint phone charge. As recently as this year I have received a phone call seeking collection. And, I tell them what you ought to tell them - fuk off! I have acquired a few cars, a house, a condo, and just got approved for financing on a $350k duplex rental property - all after having the Sprint collection problem. Point is, an isolated incident is nothing to worry about.
You can contest bad debt (sample letter -
http://www.nedap.org/resources/documents/DebtCollectionDispute.pdf). Then burden shifts to collector to reestablish that the debt is owed.
If you want the "fuk off!" message to stick, write a letter. But, I never bothered and it never hurt me. As for recourse...wtf? You're going to sue the Gym...explain that suit on your C&F application and interview...?
Finally, if you buy real property, the title company will try to collect for the bad debt at the closing. They will say some shhit like "you need to clear this up." Tell them to fuk off! too - they are bluffing, let them know you will find another title company to close the deal.