This could be because the buyer(s) are owner occupants and don't care about "the numbers," it could be that the buyer(s) are newbie investors who aren't good at doing "the numbers," or it could be that the buyer(s) have some knowledge or experience where they'll be able to offer more than everyone else and still make their desired profit.So really, it's just a competition among those outliers, not all the offers.

I'm going to put 1/2 foam insulation over the asbestos, then side over that.

You will have problems with getting self stick tile to adhere to the remnants of the foam pad underneath.

What risk are you willing to take if the house/s have issues?

I've been "no shave November"ing since college.

Let;s have a contest to see who can grow it the most or whatever.4.

Not unlike @Ben Leybovich if he stopped shaving.

First, STOP analyzing with %'s.  Have

For this refinance transaction, the borrower(s) must meet Fannie Mae’s borrower eligibility requirements as described in B2-2-01, General Borrower Eligibility RequirementsThe borrower(s) may have initially purchased the property as one of the following: a natural person; an eligible inter vivos revocable trust, when the borrower is both the individual establishing the trust and the beneficiary of the trust; an eligible land trust when the borrower is the beneficiary of the land trust; or an LLC or partnership in which the borrower(s) have an individual or joint ownership of 100%.  

If the holes are in the walls too, and not just the vanity back, then you could use some of the expanding spray foam as a possible filler.But you might just be better off uninstalling the sink and vanity, patching the walls as you would with drywall, and then reinstalling the sink and vanity.