What is the remedy for uneven walls in the bathroom, as you are tiling and run across a portion of wall that is not level?

Anything from shimming the studs, planing the studs, spackling the wall, redoing the entire wall from scratch, not using ceramic tile but flexible fake tile 4 x 8's...

Is it around the tub or somewhere else?
What's the wall covering under the tile?
Has the tiling been started and how far if so?
What size tiles?

It is the wall underneath the medicine cabinet. 4x 6 tile Thanks

... ok well you didn't answer all the questions... your wall might be too uneven for 4 x 6 tiles, or any tiles, without ripping it out. I would use the tiles somewhere else and paint the area with high gloss washable paint.

You should always do a tile layout before putting them down. Always work from the most visible squarest part of a room and go back to the least square. You can usually hide uneven walls by putting the offset tiles under a vanity or behind a toilet. You can also shim out the base trim a bit and your eye, normally looking forward doesn't pick it up. Finally, using larger tiles set on the diagonal are easy to use in crooked rooms, your eye doesn't see any straight lines.

Wonderful Learning Experience thanks. The workmen did something. Some kind of fill at home depot
The tiles look good now