wouldn't that defeat the purpose of wearing them? (To prevent sand and dirt getting into the spa?)
I've tried just about everything to prevent sand and dirt entering my tub (pan of water, etc.) but with the Oklahoma Winds, there is no possible way to keep it all out!
I guess you could take your flip-flops off and leave them on the filter compartment, or something, that way they wouldn't freeze to the deck (or cement) and you wouldn't track stuff into the tub!