If you’ve ever walked into a secondhand shop with a big box of items — then walked out 20 minutes later with a big box of items, minus two — you already know this: Sometimes selling secondhand stuff barely covers the gas to get to the store.

Still, it’s can be worth trying to make a few bucks on things you’re getting rid of anyway.

“It’s surprising what something might be worth,” said Bob Johnson, owner of the Battlefield Store. “It’s always worthwhile to get it checked out.”

Many stores recommend calling ahead before loading up your trunk, because every business has different terms and different needs. Some, for example, are exacting about age and condition. At Nu Look Consignment, 4956 Penn Ave S., Minneapolis, clothing must be brand name, no more than three years old, and free of tears, stains and missing buttons.

Others aren’t all that picky.

“We take in [golf] clubs that aren’t in the greatest of shape,” said Mike Oliver of Second Swing, 2412 E. Hennepin Av., Minneapolis.

What a secondhand business will take is based on what its customers want to buy, trends that aren’t always obvious to outsiders.

“We take our current inventory into consideration, which is totally unpredictable from an outside perspective,” said Jessi Blackstock, retail manager for Magers and Quinn Booksellers, 3038 Hennepin Ave S., Minneapolis. “We look at everything [a seller brings in], then we go on a book-by-book basis and pick and choose what we think we can resell. We pass on very good books just because we don’t have an unlimited amount of space to have unlimited amount of something.”

At the moment, for example, she can hardly keep enough copies in stock of Katherine Boo’s “Behind the Beautiful Forevers,” while the formerly high-demand Kathryn Stockett’s “The Help” “has kind of run its course.” Hardcovers are tough to sell once the paperback version is out. Encyclopedias (except for certain very old collectible volumes) and damaged books are never welcome. Bookstores have different clientele and inventories, so what one store passes on may be worth hauling to another (though if you don’t want to bother, Magers and Quinn will take them off your hands and donate them to Better World Books).

Don’t bother bringing woodwind instruments to Encore Music Shop, 2407 Lyndale Av. S., Minneapolis. But if you’ve got an old guitar, you can be pretty sure owner Chad Speck will take it.

“I would like to be a little more selective, but I tend to buy it all,” he said. “It doesn’t have to be the world’s fanciest. Everybody starts at the beginning, so ...”

It’s worth a trip to Trails End Bass Pro Shop, 7597 Minnesota 65 Trunk, Fridley, with your guns and archery bows. But “don’t hate us” if your older fishing gear doesn’t stir much excitement, said salesman Scott Panning. “Typically fishing stuff deteriorates in value very rapidly. So inheriting grandpa’s [fishing equipment] doesn’t really get you much. It’s like inheriting grandpa’s computer.”

Guns are one piece of military equipment not carried by the Battlefield Store, 3915 Highway 7, Minneapolis, Johnson said. But swords, daggers and bayonets? Sure. Along with historical artifacts, books and military collectibles of all sorts, including uniforms, medals, patches, pins, war souvenirs from the Civil War on up.

“We’ve been around for 35 years,” Johnson said. “When we first started out, a lot of our customers were World War II vets themselves, they’d bring in theirs souvenirs, turn them into cash. Now it’s their kids and grandkids.”