I'm currently treating ich and I have two clown plecs....salt added short term for medicinal purposes is usually fine.
plecos living in salted tanks isnt fine
this is a link to faq at planetcatfish
http://www.planetcatfish.com/faq/index.php?qid=103&frommostrecent=yes
planetcatfish and plecofanatics are both great sites and there is lots of info about salt in the forums.
The choice for me has to be to get rid if the ich as quick as poss...that means salt treatment to me,
I would agree, long term use to me is (a) pointless...dont understand why you would do that (b) waste of cash