The ear piece works but the volume is so low (due to the spill) you can't really hear the caller unless you're in a very quiet place.
I've been forced to use my speaker phone for the past 9 months.
Apples website says to never use compressed air. I’m assuming on all ports but I wouldn’t use it on any of the grill covered ports.You can use compressed air to blow debris and other stuff out.
I've used cotton swabs and toothpicks to get all the muck and other stuff out of the ear piece, but for the headphone jack, try compressed air.
.....if you want to get creative.