In the states, you hear de nada in place of “you’re welcome” everywhere. I don’t know if the Cubans in Key West use de nada. Since I’ve never understood Spanish before, I haven’t listened closely enough to pick it out. When we’ve said de nada, we’ve meant "you’re welcome", although it literally means "of nothing" or "from nothing".
In Costa Rica, the ticas say con mucho gusto (with much pleasure) and they say it like they mean it. It’a lovely sentiment. Try tossing off de nada, then toss off con mucho gusto. You can’t say con mucho gusto without at least a hint of a smile. Now de nada sounds a little rude to me. Thank you.