I don't think the bug discussed here http://firstname.lastname@example.org was ever JIRA'd.
I created a simple domain class:
and scaffolded it. I then created a new book from the UI with a valid title and author, but a price of "12.99skdfhaskfjh". No validation errors were triggered! The "skdfhaskfjh" suffix was silently removed and the value saved as 12.99