No visit/inspection until under contract

[Charles Royale]

I am pretty new to this, so bare with me.

My agent recently called me to discuss a pocket listing she has. One investor plans on selling 69 of his properties and just hasn't listed them yet. He plans on listing them later this week. He sent his agent the list and in turn my agent learned about them. She took me on a tour of the area and I saw most of the ones he's selling.

Here's my problem/concern. I found a few that I was interested in, but the investor isn't letting anyone into the properties until they are under contract. I am not comfortable putting them under contract without a better idea of what I'm getting myself into. My agent said once they're under contract and I inspect them, then we can negotiate, but that worries me. What sort of contingencies do I need written into my contract so that I don't get stuck buying properties that I don't want after review? 

If my question/concern doesn't make sense just let me know. I'll adjust/rephrase it.