grilles on or off the speakers??

As most of you are aware, there are a number of speaker manufacturers that claim a "specially designed" grille for their speakers, that prevent edge diffraction and whatever and do no recommend they be removed.

Since no women were inviting me to the Caribbean, and having nothing better to do, I decided what the heck and put the grilles back on my speakers. I anticipated no effect, but they sounded different. They went on and off several times, and there is clearly an auditory diffence...not necessarily better or worse either way...just different

SO, what do you think, grilles on or off, and are specially designed grilles snake oil or science??

Thanks