Overall I think STR were slow to gain popularity in SD, but now I am seeing more saturation.

I do know there has been an increase of saturation in STRs in popular areas and I hope new investors and those using the sublet model have put contingencies in place because I believe they will be hit the hardest.What do you think will happen to the sublet STRs Over a long down turn?

Found out today that previous buyers pulled out due to septic being very saturated. 

Unless you were talking total and heavy saturation it's likely to be dry in no time - the sun beating on the roof creates heat, which transfers to some extent to the sheathing below.

Eventually a market gets saturated (for the time being) and can't sustain price increases (in the short term).   

My last thought on STRs is market saturation.

Is that area saturated already, causing hosts to lower their prices to be competitive?

Do ya'll think these markets are saturated or still opportunity? 

Florida is getting pretty saturated, so just be cautious. 

If your city is saturated and/or overpriced start looking at where the new builds are kicking off and locate the nearest city to that.