Are Property Inspections a Scam?

How much you do you know about the condition of a property that has to be safe and habitable? 

If your answer is anything less than "I have flipped hundreds of homes. I can tell just by looking at it," you need a property inspection. 

I am currently looking at a very nice property in south Brandon, FL. The inside and outside look really nice. It has all of the windows and a nice faux stone on the front of an otherwise block house. The inside has nice tile through most of the house and nothing a good scrub couldnt fix in the bathroom. You can tell it has "renter's big lots laminate" in the bedrooms, but who cares?

I new the roof needed to be replaced just by looking at all the rotten fascia. It was easy to see patching throughout and the inside has old water stains to match. I can budget for that.

The AC didnt even attempt to turn on and the unit was over 15 years old anyway. I didnt have borrowed time on that. Costs are starting to add up.

I had a trump card. Good friends of mine are licensed contractors and can do all the interior stuff like the paint, baseboards, floors, doors, for cheap. 

Do I still need a property inspection? I ordered one anyway. I am an agent and the contact was easy.

To make a long, scary, story short:

Aluminum wiring
cast iron sewer line
different types of piping throughout.

Everything that was expensive is bad on the house. My budget quickly doubled and now I am renegotiating with the bank. If I cant get a better price, I have to walk away. Plus, they will have to disclose everything wrong with the property. 

My $400 dollar investment could save me from a bad deal or a lot of money from the sale's price.