Causing the unit to sit vacant with no income for the winter.

Nothing in your revised offer would be new information that causes them to reevaluate the pricing.The rent amounts should be in the leases, so there shouldn't be any question about GPR once you're under contract. 

There must be a cause for mold growth, and that cause is almost always moisture.Check there are no roof leaks or attic window leaks.

Regarding finding "deals", read below:The Real Estate Crash of 2008-2010 caused real estate prices to crash across the country - but didn't affect rent amounts.

They went upstairs and found out that the HVAC unit was clogged two floors above us that caused the water to leak into our unit.

This will cause more supply and less demand = lower prices.Of course, none of us have a crystal ball, but that is just my two cents for economics 101 :)

This is causing a huge influx of people moving here for jobs.

That causes the light switch to flip and they go back to screaming.

It also causes a lot of friction. 

Actions determine whether you have cause to terminate an agreement, for example not paying the rent.