"is it just me, or do they go unsavoury looking after a bit?"

To mangle the old song, "If you get cranky without your silk hanky,/You better steer clear of the harmonica". They can get pretty grizzly-looking without cleaning, which doesn't bother a tough guy like me - on the other hand, I do spend about half the year suffering from apparently-undiagnosable viruses, sinus infections, respiratory ailments, etc., so maybe I'm a walking - and occasionally bed-ridden - object-lesson.

Anyway, if you really want to know about cleaning, soaking, etc., (of harmonicas!) check out these guys; they love to talk about that stuff: http://groups.yahoo.com/group/harptalk/. Take a skim through the posts, or the archives, and it won't be long before you come across a relevant discussion.

And you're right; it's not a cheap instrument to play, in the long run. You'll find arguments about that as well ...