Can I paint sheetrock that has never been taped and sprayed?

You really need to tape and mud before painting!

http://homeguides.sfgate.com/paint-drywall-garage-interiors-51575.html

Sheet rock with out the proper prep looks rather bad. it Can also suck up paint. Tape and mud will give you a more uniform appearance.

You don't need to spray a texture on sheetrock, just primer and then paint. I would tape and mud the seams for a nice finish or it will bug you later. https://www.youtube.com/watch?v=_Z5IT08P01o then sand smooth. Personally, I like the mesh drywall tape.

I agree! Tape ,mud, prime, and paint.

Yes, raw sheetrock will suck up your paint and make it look blotchy, not to mention needing more paint! If you can operate a garden hose sprayer, you can rent and use a primer/paint sprayer. IF you're spending a lot of time in there, make it something you'll like to look at (Just move or cover very WELL everything in the garage).

Hi,

Use an oil based sealer paint - Zinniser 3 in 1 is a good start then just paint over it, if you don't the liner paper will contrast against the taped joints and bleed through the final finish,

Good Luck.