You're right.
"Tropical" refers to a location, or the plants that are native to that area.
Color has nothing to do with it.
True, many tropical flowers are very bright and perky, but, then, so are many temperate flowers. Some tropical flowers are even white.
It's all about the original location where the plants grew. This will also dictate, to a great extent, how well they'll grow in your area.
If you're in a cooler spot with lame sun, you might be stuck growing tropical plants as houseplants or not at all. Some adapt well, though.
Ask around and buy from reputable greenhouses, nurseries, or farmer's markets to ensure the plants are actually growing in your area. Some super-stores or garden centers get plants from faraway places and they're not suited to your location.
Ask your neighbors, too.
