Shirley - here are my brainstorm ideas- just writing what pops up in my mind.
What about customwashableslips.com would eliminate the sure-fit comparison. Or what about something like removeable upholstery with washable thrown in.
I can't believe it's a slipcover going off of the "I can't believe it's butter" commercial. Kindof too long- www.icantbelieveitsaslip.com. I will keep thinking of more.