I am just wrapping up 30 years in law enforcement and while its only semi-related, I completely get how the sacrifices often go unnoticed - I truly believe they are appreciated by most but being safe here in the USA is just expected so it becomes the norm. 

Most small businesses don't have good accounting practices, which allows problems to go unnoticed for long periods of time.

True it was, but some thing go unnoticed when you see an apartment at night. his offer was to vaccuum it.... now we are not moved in yet, we cant move in - until the work is done. he said if I feel this is not going to be the apartment for me, to let him know..

And that's what goes unnoticed by the masses and the uneducated.

You sometimes just need to STOP and smell the roses otherwise major things will go unnoticed and you will make big mistakes.I had to bring new contractors on board that I never worked with before to start on all of the extras.

But water "usually" if not done correctly will have a tiny leak that will not be unnoticed if you follow these plumbing steps 1.shut off water 2. make sure your pipes are clean 3.make sure fitting are tight 4. solder correctly 5.check fitting to see if the solder reacted into the fitting (fitting sometimes come pre-soldered)<-- i dont recommend these but can be used!

Does that trigger issues with the lender, or does it generally go unnoticed/without incident?

It's relatively easy to route for replacement purposes and is a good DIY option if you're inclined.You wouldn't want to spring a leak within a wall unnoticed!

I question every investor I work with on repair/rehab costs because it's a difficult thing to pinpoint, and it's the nature of rehabs that one unexpected or unnoticed item can torpedo a rehab budget. 

The fact that bookkeeping errors by the city can go unnoticed for that long is disturbing.And what a disappointment!