Good point Carl.

Richard, here's an interesting article on CSCC (Chloride Stress Corrosion Cracking) that led to the failure of a stainless steel roofing structure over a community pool due to corrosion:
http://www.imoa.info/FileLib/swimming_pools.pdf

Here's a good link for general info on the different types of stainless:
http://en.wikipedia.org/wiki/Stainless_steal

It's hard to find Stainless Steel types listed on vendor sites for pool ladders, but most are advertised as 304 with a mirror polish.