he's probably right to spot clean something. i wouldnt use it that much but if you have something that doesnt come up i would try.
a few years back i had some white plastic sitting in my back seat in the hot sun over night/mourning, the heat and imprinted the square white mark of the plastic in the black leather. the only thing that would get it out was WD-40 and then i treated it w/ cleaner/protecter over it.
so like a blood stain, or oil spill or something deep in there, it would probably work, but NOT for a full on cleaning session.