Worst I ever run across was the large tanker;
I fully understand that a tanker has a lot of tanks (hence the name) that can be used for counterflooding and provide more buoyancy than the average merchant ship, but it's a little ridiculous when everything but the tops of the masts is underwater and it's still not "sunk".
Heavy cruisers are the worst though;
I should be able to sail off and chalk this one up as sunk, even if a rescue tug was nearby they would consider this too badly damaged to tow and would scuttle it themselves if it didn't go down. Which by all that's holy it should, this thing is a wreck.