Can someplace be a tourist trap if you don't pay money to see it?

I assume you mean the Strip. When my daughter lived in Vegas, the only time she went to the Strip was when she got free show tickets from work, or when we took her and her husband to brunch. When natives gamble they go to one of the casinos not on the strip.
I’m not sure if Fremont Street counts as a tourist trap also. Probably.

No, I meant the entire city of Las Vegas, by the metric (proposed by another poster) that a city qualifies as a tourist trap if its economic basis is almost exclusively tourism and related industries. I think Las Vegas qualifies for that.

44% of the jobs in Vegas are tourism based. However 25% of the economy of the state of Hawaii is tourism based. Is the entire place a tourist trap?
When we went to visit her we hardly saw much tourist stuff. But we drove. The airport is end to end slot machines.

Your definition based on economic basis would qualify Vegas as a “tourist destination”. That is, people make Vegas their endpoint when going there. Most don’t “happen to stop by” because they’re in the area (because there really isn’t much in the area ;-). Yes, I realize that many stop in on their way to places like SLC, or Zion, or the north rim of the Grand Canyon.

When I think of a “tourist trap”, it is some attraction that lures you (and possibly some of your cash) while you are on your way to your intended destination. A place like Reptile Gardens (which I happen to like) qualifies as most people are really on their way to see Mt. Rushmore when they stop in.

The best example of this that comes to mind is The Thing in Arizona, just west of the border with New Mexico on I-10. There is nothing to draw you to this particular location, so 99.9% of the people who pass through on I-10 are doing just that: passing through. But from hundreds of miles away, there are billboards enticing you to find out just what The Thing is. So after hours of desert driving, as you find yourself needing either gas or a bathroom break, you find your curiosity has gotten the better of you. And you decide to pull off at The Thing exit. (but unlike the OP, you do need to pay for this one). The point being is that it is a “trap” because you wouldn’t be going there just to see it, you would be passing through.

So, what I’m hearing is that if it DOES have a basement, it’s NOT a tourist trap…