Usually, the people who say such things confuse 'object-orientedness', which is a programming methodology, with one or more implementations of that methodology.

Perl is not C++ or Java, of course (which are the two languages that are most often touted as the examples of 'true' object-oriented languages by the naysayers), so it seems unreasonable to assume that Perl should follow one or the other's ideas of what object-orientedness is. I suppose that Eiffel enthusiasts could feel that C++ doesn't support design-by-contract natively, and so isn't a 'real' object-oriented language, either.

Just rest assured that despite people's claims that "Perl's just a scripting language", there are many of us who develop object-oriented Perl every day.