Stupid Bathtub Tiles! And Grey Stuff!

Is there a rider on Murphy's Law that says something like "75% of the time you start a simple home project, the rest of the iceberg will pop up and bite you in the ass."?
~
I try not to look at my husband's bathtub, but when I do I always shudder and clean it. Recently it had reached that point of no return where no matter how much X-14 you sprayed on that caulk between the bathtub and the tiles, there was always some grey left. I hate grey caulk spots. Yuck city. It can smell clean and you intellectually know it's clean but when you can see the grey, it just doesn't seem clean.
~
My Sweetie left Monday morning to go to L.A. on business so I thought it would be a good time to strip out that gross caulk. When I was working in the front corner, two tiles were loose, so I thought I'd popped them out as it would be easier to clean them. Oh my!
~
The "dry"wall behind those tiles had obviously been wetwall for quite some time. I was met with a big oddly colorful mess of mushy weird yuck falling out of the wall. After I knocked out the loose fluffy stuff, I still had this left:
I worked for some time getting that stuff out and found out there was wood back there:

That was good. I had some random pieces of drywall left over from when the plumber rerouted our hot water pipes after the big leak a year or so ago and cut some out and put those in:

And if you wondered why I used the plural just then, it's because that wood back there was two drywall thicknesses away so I had to do layers. A lot of that weird colorful moldy old wallboard goo was stuck on the back of the two tiles I pulled out so I soaked them for several hours in soapy water. The smaller tile cleaned up nicely but the larger tile had a thin layer of what seemed like cement on the back. I had extra tiles, but when I pulled out a nice brand new, non cement covered tile, I realized that the one from the wall had been cut. The new tile was too big.

~

I spent several hours today with a hammer and small screwdriver. I used the screwdriver as a makeshift chisel and bit by bit, pounded that layer of cementy stuff off of the back. I realise I could have figured out a way to have a fresh tile cut to fit, but I figured out the chiseling was good honest labor. And I pretended I was an archeologist finding a rare ancient treasure. Those guys must have hand muscles that I didn't know existed, because my hands are killing me.

~

After I got that stuff off, I replaced the tiles and then several hours later grouted them:

It will need some touching up and cleaning, but the grey is gone and that is good. I hate that grey stuff.