Why ( provide reasons ) people "LIKE" to walk on floors "BAREFOOT" even IF ( on the condition that ) the Floor ISN"T CLEAN ..... the question is asserting the action of walking on a floor "BAREFOOT" is related to "CLEAN" ..
.. what is a FLOOR ? a lower inside surface of a room... a Floor could be soil ( dirt) tile wood metal stones marble slate clay cement bamboo cloth carpet straw woven or unwoven ....is it ALWAYS or even about LIKE ...people walk on a floor because its the Surface to ENTER and BE in a ROOM ..
...PEOPLE also walk BAREFOOT NOT in rooms but out in the environment ....some people like SHOES or foot ware,,,,and the PURPOSE of Foot ware are either FASHION , or FOOT PROTECTION .( avoid injury trauma or skin temperature issues )
one does know human FEET have SKIN have BACTERIA on them plus oils in the skin attract dirt and could transfer actually more bacteria than shoes
plus can harbor FUNGUS of the skin and toe nails because it has temperature..are susceptible to cracks and cuts in the skin . being invaded by skin boring organisms or parasites also produce sweat ( moisture )
Now DEFINE CLEAN , what is CLEAN . its more a question of STANDARD of QUALITY
one dictionary states to be free of "dirt" marks and stains