A trick for buying swimming goggles

If you’re at the store, looking for goggles, here’s a trick to tell whether they’ll actually keep water out:  put them on without the strap.  Make sure there’s no hair under them.  If they’re a good shape for your face, they’ll stick at least for five seconds without the strap.  The ones that I have stay on, even without the strap, until I pull them off.  They’ve never failed.