I had a tenant for 3 years that always paid the rent on time, was polite and respectful, then left the place a disaster when he and his family moved suddenly.

Buyers are surprised when a deal that has been going well in the back and forth suddenly dies because someone appeared  and made an agreement.

We then cut the vegetation away and suddenly the backyard was simple and clean.

When we first started looking at multi units (with zero managing experience), all of a sudden we qualified for a couple of $600+k 4-plexes because the income from the units were factored into the banks qualifying equation.

All of a sudden they are wanting to “re-discuss” the lease because the neighbor’s dog barks a lot and they play music in the middle of the night ie 2:30am until 5:30am quite often - week days, weekends, it doesn’t matter.

Why suddenly such concern for a seller?

Some companies grow too quickly and suddenly are no longer offering the stellar service they once did. 

I don't see any realistic scenario where rents drop suddenly and drastically.

It is Tenant's responsibility to reach out in case of a sudden hardship or event.

The stark reality is that a 30% market downturn, again caused by an unprecedented surge in interest rates – the highest in four decades – can profoundly affect market values.