The vast majority of those people are exaggerating their successes.

The vast majority of contractors won't want to give bids on properties while under contract unless they have a relationship with that person from prior jobs.

that we’ve learned in our 24 years, managing almost 700 doors across the Metro Detroit area, including almost 100 S8 leases:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+ (roughly 5% probability of default), zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680 (around 10% probability of default), some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.

it looks like you have found out - correctly - that the vast, vast majority of properties for sale aren't good deals from an investment perspective. 

I am guessing that the vast majority of homes 10+ years old had some sort of water damage at some point, most had probably several.My own home is only a few years old and we had the washer spring a leak and a few years later the RO system in the kitchen started leaking into the cabinet.Seller disclosures are pretty useless in my opinion.

What are the main reasons condos are considered vastly inferior?

I believe a large amount of our ad spend was spent to advertise the program.

Here you will get a vast array of perspectives.

The vast majority of licensees don't do any business.

Real Estate Investing is for the vast majority of time not classical "investing", it's a business.