I also have an addendum attached that describes examples of activities that may become necessary that are unforeseen at the time of making the lease which may require additional administrative functions that cause additional charges to be assessed that become a part of rents then due.

I analyzed the property with 50k extra to account for any unforeseen rehab costs as well.

The DIY route has additional risks (choosing a bad deal in the wrong area, rehab issues, unforeseen structural or systemic problems etc) but you also have the potential for higher returns via forced equity.

We always keep reserves for unforeseen events and we buy properties that have multiple exit strategies.

Military personnel are frequently forced to relocate due to changes in their duty stations, making compliance with the two-year ownership and use tests difficult.A partial exclusion is available under IRC section 121(c) for taxpayers that are forced to sell their home before satisfying the two-year ownership or use requirement due to change in employment, health, or unforeseen circumstances.

If liens (or encumbrances) are found, then the title insurance covers anything unforeseen NOT INCLUDING the discovered.

-Have they ever come back to bite you in some unforeseen way?

After rent has been paid on the first, the issue will be handled.. although the story gets more interesting but I will wait to explain this until its taken care of incase some unforeseen action occurs. 

Then there are the unforeseen things like a good tenant going very bad or a sewer issue. 

@Mindy Jensen Divorce is an unforeseen circumstance and allows for a prorated application of the gain exclusionPartial Exclusion May Be Available If you don't meet the eligibility test, you may still qualify for a partial exclusion of gain if you moved because of work, health, or an unforeseeable event.You can qualify either by meeting a set of standard requirements (the “safe harbor” provisions) or by showing enough facts and circumstances to validate your claim.Unforeseeable events.