Works well if installed properly.I had a property with pex and either because they were not crimped properly or for whatever reason, there would be a slow leak and the slightly acidic water (well) would eat away at the fittings, causing many leaks and replacements. 

I would acid wash it to clean it up and seal it with a low luster stone sealer.

AND, this is after she listed with another agent before who listed it for $30,000 more than it was worth (roughly 10%) and that hurt the price of her home too since we all know days on market is like acid to the price of a home.

After than we ended up doing the acid etching and painting. 

This is, almost by definition, characteristic of cultist behavior and demonstrates a lack of critical reasoning skills.There is also the blanket "uneducated" statement that gets tossed around when the "liberal" one fails the acid test.

Most of the ones I see really aren't any different one from the other.The acid is test is how well you were able to monetize the material you received and quickly. 

So, I tell everyone who asks about this product because yes, you can cover and seal and and and, but cleaning will not get rid of dog pee, and now I know it is an alkali when it dries, I know to use an acid to help  clean it (vinegar), and the enzyme to digest it. 

Certainly, in our neck of the woods (we have acidic soil), almost every tank will be completely corroded after 30 or 40 years.  

Also;  unless you have perfect soft water in your area tankless water heaters require a fair amount of maintenance - annual acid flushing and so forth.

You have to remember though that vinegar is an acid and will etch the grout.