I've done the wet cloth tricks, the old toothbrush vent cleaning routine... . These methods simply take too long in IMO, and didn't produce the results I needed... . to impress a judge.
Even if your not entering a show, I recommend the following steps... . to impress yourself.
1st. Remove the floor mats, and beat em against a wall if they are made of carpet. Wash em if they're rubber.
2nd. Vacuum everything, as you normally would. Assuming you are thorough (under seats, the seats themselves, floormats... . etc... )
3rd. Position vehicle broadside to the wind. Open both doors, and use your air compressor on just about everything, including the carpet and seats. Start on the upwind side. and work your way downwind. Remember, compressed air can be rather powerful and potentially destructive. So I don't recommend putting the nozzle against somethat that may peel away. Stickers, etc. .
If you don't have a compressor..... or a breezy day. Hopefully your wife has a sweeper with one of those little round soft bristle brush attachments. Works almost as well. Great between the radio buttons and vents.
BTW: Your shop-vac is out of the question... it uses course plastic bristles. Do not use anything with plastic bristles. Most quality household sweepers use horse hair bristles. VERY GOOD!!
3rd. Lexol on leather, vinyl-x on dash, doors, etc. . (My preference) Both products made by same company. Stay away from ANY silicon based products. (read the label). These products "generally" produce an extrememly shiney... . un-natural finish. . (judges dislike)... Not to mention the glare it produces.
Besides, silicon actually dries everything out, rather than moisturizing. AND its the stuff that creates that nasty haze on the inside of your windshield. Ever notice how the haze is worse in summer??? Heat+Silicon=Haze.
4th. Newspaper & glass cleaner for the windows. Unforunately, this trick doesn't work if you have film tint nor should it be used on dash gauges which are plastic... . not glass. (scratches) Factory window tinting is fine.
5th. quick run through with the compressor again to remove any lint or newspaper particles that may have been left behind. This step should require no more than 45-60 seconds at most.