I attended a Show this past weekend. They asked everyone at the registration/entrance booth if they wanted to to be able to touch the quilts...if yes, they were given a pair of disposable gloves. They can be bought at Walmart, etc. Pretty inexpensive.
Perhaps a nice sign upon entering the show EXPLAINING why quilts should not be touched but do it in a nice informative tone. Nothing puts me off like a rude sign. (no shoes,no shirt NO SERVICE"... Yikes!). "Negatives" puts me on the defense. Productive information is positive. Informative and educates.
Sandy