My advice - find somebody who shares similar ideals for clean code, that way you have an ally. Don't force your ideas upon people, but just suggest small changes at team meetings - start with source code control - suggest that you should have a backed up CVS server (or some alternative revision control engine). And follow it through by simply installing one in your lunch hour - otherwise nobody is going to use it. Show your boss how great it is to get commit emails showing you what has changed and who changed it.

Once you start to bring improvements like that to the company, you'll soon find that you are both trusted, and that your probation period is very quickly over.