Personally, I prefer not to use commas, I simply use spaces. There's a reason for this, IMO.
Search engines read the comma as a "stop" and a "separator" for your keywords. Thus:
"hunting camp, camp rentals, fishing camp, ohio camp"
Will produce these keywords in the seach engine's mind:
On the other hand, if you use spaces, you are not predefining how the phrases should be broken up. The search engines will instead break them up as needed to fit the keyword phrases that are seached. So, if you have this tag:
"fishing hunting camp rentals ohio"
The search engine can pull any combination of phrases from the list...
fishing hunting camp
hunting camp rentals
fishing camp rentals
camp rentals ohio
hunting camp rentals ohio
Plus, you've got less words, so there's on fear of "repeat/spam" issues, or of lowering your density.
But, it's personal opinion, there are advantages both ways and every SEO has their own style.