Just a general lack of demand caused by general conditions.

So, my intuition is that C class will continue to be in high demand for a few years as people determine their new economic realities. 

The mixture with low interest rates compressing CAP rates and demand for retail space diminishing, we will more than likely see stagnant rent growth and rising cap rate (as interest rates increase).

The demand in Fairfield County for rentals is very strong - I'd love to do a BRRRR there but would want to buy it with my own cash. 

I know losing a few percent to a realtor feels like its going to cut into your profits but a good realtor will bring so much demand that you will get more than 5-6% extra in your selling price and offset the cost of using a realtor. 

From there, see what the supply and demand is in your area.

Since first time homebuyers cant/wont buy occupied properties you are only competing against other buy/hold investors which decreases overall demand. 

Are there other 3 bedroom unit duplexes in your area or at least townhomes to evaluate whether a demand is there?  

Figured there had to be more folks like that in the world and made it my business to find them.Class C is always "in demand" whereas higher end properties (Class A) can see less demand when times are tough.  

I just want to know how to analyze like how to find out if the demand is high, how do you know if homes are selling fast, how to find out if demand for property in any area rising or falling or how to find out if a neighbourhood is hot or not, I've discussed with a lot of people and they recommend me to use city-data.com which is an excellent website to know about the market but even in that website I don't know what to look for like if the population is 20000 in a city is it good or not or what it should be or what should I type in google to know about a specific market or place?