It's not uncommon for Fannie Mae and Freddie Mac to exclude accessory unit rental income from DTI (Debt-to-Income) calculations, even if it's been reported to the IRS.

Failure to disclose is a tall bar in the court room.Allow me to address each of your items:Water in the basement is not uncommon at all, and it likely is a simple fix.  

In our experience, rooming houses tend to serve very specific demographics, such as:students - we operate a rooming house which serves international students attending the local universities;{a specific} work force:  It is not uncommon to find rooming/boarding houses in close proximity to major employers (factories, hospitals, fish plants; etc);seniors:  A rooming/boarding house which serves seniors;the displaced & transient:  Rooming houses which serve those on the fringes of society (mental illness, transient, addictions).The population you serve will very much dictate the type of operation you will run and each comes with its own management challenges and rewards.My third question is, "Is this rooming house compliant with local zoning and bylaws?"  

Your experience is not uncommon at all.

If its before 1977 then you are fine to build as you follow those guidelines.This is not uncommon actually as what they want is they do not want someone combining multiple lots for multiple properties.

So thats why I would have thought that CGT would be established from the date I took ownership and forward.This is an uncommon situation because typically FMV and transfer of ownership would be fairly close together and not 4+ years apart with such a major difference in asset appreciation.

It is not at all uncommon for offers to be submitted in the name of "Joe Smith and/or assigns"... you just want to make darn sure that if you're Joe Smith, that your partners are going to actually deliver their capital or that you have the ability to close some other way if they don't. 

It is not uncommon for people to sleep on a deal and then wake up in the morning with a change of heart. 

You will find more people doubling up because they can't live on their own or staying with their parents longer, the same way you see in Europe where kids with their parents into their 30s and 40s is not uncommon. 

My sweet spot, from experience, is ensuring that 70% of the current market rent covers the property's debt, uncommonly when projecting rent increases of 3-5% annually.