I am under contract to buy my next Brrrr, but this one has such a strong smell of cigarette smoke and Cat piss (in some areas).

Fast forward to today and we list the home, get it under contract in 5 days, and then the buyers terminate the contract because the foundation.

Second, it shouldn't matter to you whether the wholesaler buys the property themselves or simply assigns the contract to someone else. 

I see a lot of wholesalers put a property under contract and try to flip it to another buyer before they own it.

When a target property surfaces, be prepared to act on it within HOURS not days.Be prepared to show a solid proof of funds (not a print-it-yourself POF from a hard money site) and to submit a reasonable offer (most likely 97%+ of asking price).And if you have a good agent, you'll get that property under contract and start you due diligence. 

However, I would like to have wording in the contract that specifically states we will either find another buyer or contract becomes null/void , allowing us to walk away from the property.

In contract on a property for myself at the moment so do not have enough cash for another rental.  

@Michael Wentzel I'm wondering how does an assignment of contract work??

One that is familiar and comfortable with: Double escrows Assignments Wraps (sub2's, Contract for Deed)

I have contract signed.