I don't have the time or patience to wash a washcloth after every use. Loofahs dry out more quickly than washcloths or sponges (I'm talking the plastic artificial ones). I'm sure it could get gross, but I throw them out before they get too bad. You can wash loofahs in diluted bleach every few weeks to keep them clean.

You mean the plastic ones or the real ones? The plastic ones you can hand wash but I wouldn't stick it in a washing machine (you probably could if you used a laundry bag and put it on low spin)

I just replace mine often (each week) since they're only like a dollar or two, personally.