It seems that waxing a dulled acrylic poly finish is a no no. Why is that? What are my options for bringing a lustre back to my floor without screening and re-coating? Thanks.

Stocking feet will polish a floor, if it is not worn too much. If the floor looks good right after you clean it, when it's wet from the rinse, and then looks dirty again or dull, plan on a re-coat instead of a surface shine. You may have adhesion issues if you put some type of shine on the floor instead of re-coating with floor finish.