Agreed - the amount you get (last I checked) were so low that you could spend a year doing them over and over and would make about BTC0.01 which is just over $2.4USD at time of posting. It really is only useful for newbies who wish to experiment initially before moving onto bigger things.

Also, IIRC having dust in your address means that you might actually require a larger tx fee to be included in a block anytime soon - which itself might outvalue the value the of dust you have.