Handling bounced spam messages

[Mark Constable]

The admin users of mine and vhost domains get bounces back for
all sorts of reasons and they often go into an unsure folder
until trained not to. What bothers me is that by retraining
these bounced messages to be ham I suspect I am destabilizng
databases and polluting them with highly spammish tokens from
these bounced spams.

Is this really a potential problem and can anyone suggest a
good strategy to deal with bounces and otherwise spammish
admin messages so that obviously spammish tokens do not get
relearned as ham tokens ?

(Sure, I could try some variations but I thought someone else
may have already tackled this and have a reliable strategy.)

--markc