i sew in the basement on a concrete floor. yay! when we moved into this house there were carpet tiles, the ones that self-stick. i kept losing pins, i couldn't roll my la chair, and i was leaving a track between the door and the quilter. i couldn't rationalize taking it up, because it was so warm and sturdy. there was also a mildew-y smell that we couldn't find.
the washer overflowed and left a puddle that you cold row a boat in. after we shop-vacced the water out and took out all the wet carpet tiles to dry (they never did), the mildew smell was gone forever. i forgot how damp basements are and how carpets retain odors. as for the tiles, before they could dry on the deck, it would rain again. because they have heavy rubber backs drying takes forever. if they didn't stink we would have used them in the garage (the cars never get in there - no room LOL). i think the concrete floor in my basement would always have been too damp for carpet. my dh used a sanding machine, did the best he could and we painted the floor. no smells, easy to sweep, easy to roll the chair, and no lost pins. i wear warm socks and rubber-soled shoes. in the summer it's nice and cool.