1. If it smells musty now, it’ll reek forever.
A damp-smelling garment isn’t dirty; it just hasn’t been stored properly. Airing it out will usually take care of odor. Or try storing it with an open box of baking soda. Steer clear of soaps with dyes and perfumes and harsh chemicals like Febreze, which can damage older fabrics.

2. A torn seam equals a lost cause.
A good rule of thumb, per Laura Wills of Screaming Mimi’s: “Anything that’s on a seam can be fixed.” Under the right circumstances, even damaged fabric can be repaired. For moth holes, Wills recommends French American Re-weaving Company (212-765-4670).

3. That dress is so old, it must be falling apart.
It’s always a good idea to give a piece a once-over—checking the knees, elbows, backsides, cuffs, collars, hems, and armpits for rips, frays, and discoloration. But you can generally assume that a seller has inspected an item before it ever lands in front of customers.

4. You’ll never get that stain out.
Chris Paulocik of the Met’s Costume Institute recommends taking a stained garment straight to the dry cleaner, since many home remedies, like club soda, can actually make a stain worse. (Sweat stains, she’s sad to report, are pretty much untreatable.)

5. These places are crawling with bedbugs.
Compared with new-clothes retailers, vintage shops have had few incidents. The reason: “If it’s a good vintage-clothing store, we steam-clean everything,” says Wills. Plus vintage shops rarely accept returns, another way bedbugs infiltrate stores.

Related:

• Archive: “Fashionables”
• Articles by Jillian Goodman
• Table of Contents: Oct 25, 2010 issue of New York | Subscribe!