Lots of times, Class::DBI is used in web-based applications. (In fact, coupled
with a templating system that allows you to pass objects, such as
Template::Toolkit, Class::DBI is very much your friend for these.)

And, as we all know, one of the most irritating things about writing web-based
applications is the monotony of writing much of the same stuff over and over
again. And, where there's monotony there's a tendency to skip over stuff that
we all know is really important, but is a pain to write - like Taint Checking
and sensible input validation. (Especially as we can still show a 'working'
application without it!). So, we now have CGI::Untaint to take care of a lot of
that for us.

It so happens that CGI::Untaint also plays well with Class::DBI. All you need
to do is to 'use Class::DBI::FromCGI' in your class (or in your local
Class::DBI subclass that all your other classes inherit from. You do do that,
don't you?).