If I use one of my freshwater reels, in saltwater will the saltwater ruin the braided line. Like will the line loose color or anything like that

I'd be more concerned with the hell saltwater will wreak on a freshwater reel.

I use the previous model Shimano Sienna in the surf because they're cheap to replace, but I haven't had to replace it yet after 4 years of off and on use.  Saltwater doesn't seem to fade the line any faster than freshwater, but you must rinse the reel (and rod/guides) thoroughly in fresh water after using it in the surf, as quickly as you can find fresh water.  I took the reel apart for maintenance last year and other than having down to sand down a rough spot that was developing under the spool, it's still perfectly fine.

Never had a problem with saltwater damaging my braided line. Clean the braid with freshwater after your saltwater fishing trip and do the usual reel maintenance as needed.

21 hours ago, Brew City Bass said:

I'd be more concerned with the hell saltwater will wreak on a freshwater reel.

Most decent freshwater reels can handle some some saltwater fishing if you take care of the reel. I use the same reels for snook fishing that I use for bass fishing and my reels work great.

Most of my spinning reels see double duty and I have never had an issue.

That's a negative. We've seen no issues with braid in salt/fresh.

I use a quite old Stradic every year in salt with braid and have had no troubles.  But I have the reel well oiled to begin with, rinse thoroughly every day after fishing, and when I get home, drag the line through fresh water behind the boat.  i think if the salt is left well inside the line stack it can get "sticky" and not peel off freely, so I try to get the salt off the whole line.  Same for fly reels and rods.  The color on some of my braid has changed, but does so in fresh too, so don't know if salt is worse for that.