Perl Black Book 2nd Edition
I can't comment on the Perl Black Book, but I had the Java one and it was one of the most unmitigatedly dreadful computer books I've ever read!
I guess that my preference when training people is to have
high quality(OK, I probably mean O'Reilly) reference material about. Much more important, though, is access to someone else who can support them to learn. Ideally this would be a more experienced developer acting as a kind of mentor. Perlmonks and similar communities can act like an 'online mentor'.
That all having been said, I always hang on to books, because at some point they'll have something useful in them, even if its just to serve as a warning never to write technical documents like
this ;-).
As Günther Grass said, "Even bad books are books, and therefore sacred".