So it's any property considered unstablized if it's 50% vacant or more or does that term have to do with it losing money or both?

Is the soil unstable, are the drainage issues, etc. check with the neighbors to see if they are also having settling, foundation issues.

Some would argue that child support is unstable but I would argue any source of income is unstable. 

The average tenant has an unstable chaotic life full of drama and they will drag you into their mess if you let them .

It had an unstable tenant base with vacancies and non paying tenants.

Leverage can magnify your return, but it can also make your portfolio unstable.

If you take the contractor job and it has unstable income, it will be very hard to get a loan3.

I don't have access to conventional financing because I've moved around and had a very unstable income, but I've bought ten units in the last few years by getting creative and grinding it out because that's what it takes. 

Unstable jobs & lives.  

But going from intelligence to electrical they may see as unstable or uncertain.