How Much Cash Should You Have When Buying a Business?

I want to get into how much cash you think we should have when we're buying a business. But before I do, I've always been personally curious on this since your background in business brokering. So those businesses, I usually see them on places like Biz by Sell that are turn based, turnkey, whatever. Often it's like an ATM route or a laundromat. These things are often marketed like very hands off passive. Like I saw one in Texas figure out which city but together both locations were making like 30K a month. What's the grift going on here? Because I'm assuming that's not true.