The following article talks about the saturated inventory of rental units for students in the Waterloo area.

Is it saturated with rentals?

I'm worried about the area becoming saturated with too many rentals. 

I'm trying to find key indicators to look for when considering if a market is saturated with rentals?

At some point, saturation takes effect.

There are few renters who can support a store of the size and most of them have saturated the market, Lowes, Homedepot, Best Buy, etc.I am not sure about hotels and self-storage, I could envision scenarios where each could do well or suffer.  

Contracted a PM from afar and leased to likely the first applicant that could scribble their name on an application(neighborhood was saturated with rentals due to "crisis").All well and good for a few months then weird amounts of short rent start popping up - ie $724.39 where $1200 was rent.

From what I've read Tampa and Orlando have become a little too saturated with investors.

@Robert Soto, the market in Rincon is saturated with AIRBNB.

Our market has become saturated with investors in the last few years and the competition for deals is fierce.