Hi all
I keep seeing the same problem, whether it is an 12 channel Mackie or a 72 channel SSL. Unless your mixing desk (smaller version) or your full sized console is kept powered on 24/7, keep it covered up to prevent dust from getting at it, especially the faders.
This also applies to the patchbay which is arguably more prone to dust and other things (ie drinks) affecting their use as the horizontal producers table is in front of it.
Unless they are in constant use, COVER THEM UP. A plastic (or polythene) sheet is good rather than a blanket type of material which has it's own dust. It costs just a few dollars, pounds or Euros and can prolong the life of your console and save all that cleaning effort afterwards.
Even little old me, who has a few items of gear (mixers, speakers, a Roland electronic drum kit on a rack system, other acoustic drum stuff and studio type equipment) keeps them all covered up when not in use and I can't believe it when I see studios with gear unprotected in this way. Crazy!