Rinse them REAL GOOD in fresh water and wipe them down and you should be fine. I have Penn and Abu Garcia reels that I used thirty years ago in salt water (a lot) and they are still chugging along just fine. Taking a reel apart to clean it is never a bad idea.

I use a stoddard chemical solvent which is water displacing to rinse off my reels. White sprits or mineral sprits will do. WD 40 is a brand of highly refined Water Dislpacing white sprits that works just fine. (WD 40 stands for Water displacement perfected on the 40th try). All reels that use a one way bearing are very subjectable to rust in the one way bearing. The cheeper bearings are usually made from steel which is subsepable to rust, but the better bearing themselfs are made from non-rusting stainless steel. Yet the inner race that they BOTH run on is usually made from sintered metal/steel which will rust very quickly in saltwater use. It is very important that this bearing is re-oiled after being washed with WD 40. To wash out a baitcaster, the best way is to remove the left side cover (right hand reel) and slide the spool out being carefull to not let the line get tangled. Then spray the WD 40 down into the hole in the pinion gear that the spool shaft came out of. Then re-oil the bearings and put the spool back. To oil the one way bearing, hold the reel vertical such that the reel handle is down and parallel to the ground. Then put a very generous amount of oil in the top of the star drag nut where it meets the reel side cover. Let it set for a few seconds then turn the reel 180 degrees such that the reel handle is pointed up and still parallel to the ground and hold it like that for several minutes to let the oil run down into the one way bearing. A lot of the oil will run back out on the side cover, but some will find its way down into the bearing. Then spray down the whole assembled reel with the WD 40. It will even sometimes soften old hard monofilament line just a little without degrading the polymer enough to weaken the it seriously. And on that subject, I often use Armor All on the monofilament spooled reels before being put into storage. There are very few areas inside the reel that actually need grease. The Slider and kicker mechanism are about the only part of the reel that really need grease, and a good oiling after each cleaning even works there. The grease will last several years under normal use while the oil is short term so if the grease is washed out during cleaning make sure to add a few drops of oil down the hole in the pinion gear while the spool is out to replace the grease.

Everyone is dead on. Rinse them lightly with a hose. A real good saltwater guide told me if you hit them hard than it just forces the salt deeper into the reel. Never soak them in water. I also spray mine down with some type of reel oil.