I do this sometimes. Usually when I want private data and the object to behave in public like its underlying blessed type (eg, keys %$obj). This can be more useful than having special key prefixes or other nonsense - but by Software Engineering standards its pretty poor form. Good for quick n' dirty stuff though ;-)
Interesting. It doesn't seem to me so atrocious after all. Fortunately perl is flexible enough that you can decide what is good and what is evil depending on the problem at hand in each particular situation.
The problem is that experienced hackers do know when they're doing something that is potentially Bad(TM), and they do on purpose - because they know what they're doing, while occasionally you can see newbies using the same techniques in a totally uninformed matter, which contributes to the spreading of bad programming techniques - what that sometimes in turn contributes to give Perl a bad name...