Like Mark said, dirt isn't a problem, it hasn't been for me.
What concerns me, with this species, is they are just plain too nice. Being shy and rarely defensive means, people will be tempted to manhandle them more often. Just because they are not biting you, doesn't mean you are not stressing them out by handling a lot. Yours suddenly getting sick, is a clue something's up.
For the record, I have a huge WC as an adult male, and he will not bite in defense. (I also have one that will, hehe) This does not mean he isn't stressed to heck by handling. Rudicollis just show it in other ways, IMO. Getting sick is one.
I wish these guys had biting in their repetroire more often. Biting seems to be the only communication that gets through to people. People just ignore the other signs, poor rudis.
D.