I've been told yes put black plastic in your crawl space and then was told not to. These were different contractors! What should I do.

Color doesn't matter, black, grey or clear. Covering of your crawl space with 6 mil visqueen can cut down on moisture getting into your crawl, its usually then covered with some gravel.

Bal1 correct here I just wanted to clarifie this is only on the ground and not the walls?

Is this a new crawl space?

In my area new has to have a crushed stone the 6 mil vapor barrier then a slurry cover in concrete 2" min along with radon roughed in if needed later.

Check your codes there new or old.