Don't know if this has been mentioned before, but...I REALLY don't think
Diora Baird's breasts are "fake". Watch the scene in "Wedding Crashers" where she falls back onto the bed and lays on her back; her breasts "melt" into her chest and armpit. Fake tits don't do that, instead they tend to jut out or protrude from the girl's chest when she lays down; they don't respond to gravity.
Diora's do...and I think that's a sign they're definitely real.