The magical boots of dancing will expand or contract to fit any foot size, from halfling to giant (just as other magic boots will do, of course).

They radiate a dim magic if detection is used. They are indistinguishable from other magic boots, and until actual melee combat is engaged in they will function exactly as if they were one of the other 4 types of useful boots (see below). 

When in melee combat, or if the wearer is fleeing from the actuality of same, the boots of dancing will impede his or her movement, begin to tap and shuffle, heel and toe, or shuffle off to Buffalo, making the wearer behave exactly as if Otto's Irresistible Dance spell had been cast upon him or her (-4 from armor class rating, no saving throws possible, and no attacks possible). 

Only a remove curse spell will allow the boots to be removed once their true nature comes forth.