You are going to end up with pieces of tile somewhere, where is up to you and he to get together on the layout. This should have been done on graph paper and approved by you before the tile was installed. He is incorrect on the corner condition as this should not be grouted as all changes in plane should be caulked using a color matched caulk.

A contrasting grout simply amplifies the quality of the installation. It'll accentuate a quality installation that has even and consistent grout lines. It'll expose a poor installation with inconsistent or uneven grout lines.

It's the layout and pattern. Slivers in the corners can be avoided. And they should be avoided.

The other thing with slivers is that when they are used as end-of-course fillers, they will show off any un-eveness in the wall. In your first photo, it appears (could be camera perspective) that the slivers are quite narrow at the top and grow in size as you go down the wall.

Your contractor? Based on your post it sounds like he's being reactive instead of proactive. If he knew the dark grout would show off bad corners because of tile slivers (which never should have been allowed in the first place), he should have recommended changing the tile pattern/layout before work began.

He wants to disguise bad work. His goal instead should be to eliminate it.

Just curious - what is the grout color?

Did you rip this out due to the layout issues? If he did a tiled shower floor, I would have it tested before proceeding. There can leaking into the house if the shower pan was not built well.

I hope you are starting with a different installer.

@MongoCT - Yes, the wall is uneven! That is one reason it was ripped down. Contractor blamed his plaster guys stating that he usually has the tile guy install & plane the boards behind the tile.

@snookums2 - How to test? The bathroom floor is tiled, which we did not rip out. We did rip out the shower floor due to it not being lined up.

@tinker_2006 - it is Bostik Delorian Grey

"Contractor blamed his plaster guys stating that he usually has the tile guy install & plane the boards behind the tile."

There is drywall behind this tile? What type of waterproofing system was used?

@millwokman - It is a cement backboard. But there was no plastic vapor barrier between that and the framing. (I've just begun googling steps to tile a shower). Is this a big concern?

there was also no thinset waterproof membrane over the board!!! Ahk! Just the tile.

Sorry, I was referring to the shower floor, not the bathroom floor. Be very careful who builds your shower.

I would use white caulk in the corners, not gray. This is because the tile layout should look like the tiles bend around the corners. i.e., half a tile on either side of the corner, or 1/4 on one side and 3/4 on the other side. So a contrasting caulk would cut the tile visually and eliminate the illusion of the bending tile.

Also, always caulk, not grout, when you have changes of plane.

Finally, as others mentioned, you should not have slivers of tile on the ends or corners. You fix this by shifting the tiles. So on the RH side (I assume this is your first photo), the pattern should be shifted 1/2" to the left, so that in the corner you have full tiles or half tiles, every other row. Then on the left corner the tiles will all be pushed down 1/2" so that the wrapped around portion that's now about 1" becomes 1 1/2" wide.

So there isn't a vapor barrier between you tile & cement board?

Your shower needs a waterproofing membrane on the walls AND the floor. For the walls your options are a sheet plastic behind the ceement boards on the walls OR a surface membrane (kerdi, hydroban, red guard, aqua defense et al) on top of the ceement board. But you must have one or the other. If you have neither, he owes you a new shower.

That does look awful - and the grout in the corner looks darker than the rest of the grout. The tile pattern is not planned out and the slivers look terrible. I think it would look fine with the darker grout if properly installed, but my personal preference would be for a lighter grey grout - more silvery grey - as I don't like that much contrast with grout and tile.

Where are you at with this?

I agree with Paul. He did NOT put a vapor barrier on the studs and he did NOT use a "Surface Applied Membrane" on the Hardi. This is a recipe for disaster. It might last you a couple of months or a couple of years (If you're lucky) but it will ultimately fail. He owes you a new shower....but frankly, I wouldn't use him for the re-build.

Have the next guys throw up another layer of board to get rid of those little bitty tile too.

It should have been laid out so as not to have the slivers in the first place. I would imagine he just started from full and halves and went to whatever happened in the corners. Especially with a contrasting grout, there is NO WAY this is acceptable.