After reading that thread I am vowing to go with my instincts in the future. I generally think I am too harsh in judging, but not any longer.
Things I have 'let go' that didn't work out...a guest called during our first years here and was unsure of dates of arrival, departure, length of stay. We thought, at that time, that we had to take everyone, that we couldn't turn anyone away. Guest ultimately booked 5 nights. When she arrived she could only pay for 3 nights. Her cc was over extended, she had no cash card. We took the 3 nights' payment and told her she would need to figure out how to get the rest in 3 days.
She took over the inn. Used our phone, had calls coming in all day and night, her name on her luggage tags was not the name she gave to us, people were calling asking to speak with her, she had strangers coming and going, she told fantastic stories and the coup de grace (for me anyway) was that she dressed like a hooker.
Altho no one ever stayed overnight here, there were daily calls from different men and different men showed up at the door all day and night.
After 3 days she told us she had to go home. Her husband was willing to 'work on their relationship'. We took that as a sign that our prays had been answered and called her a cab. No idea how she paid the driver. Don't want to know.
Then there was the one recently who called 3 times at midnight and when I finally spoke to her said she 'forgot' that small places don't have staff at night. We went around in circles about how many nights, her bringing a dog, etc. I was getting worse and worse vibes with every contact. She showed up at the door at 10 AM dressed in her pajamas, with the dog tucked under her arm, trying to check-in. We were serving breakfast. We ended up cancelling her rez on the spot, forfeiting $800 just so we wouldn't have her in our house. (The person she stayed with is still talking about her.)
OTOH, I totally misread a wonderful family who came for a wedding. They were so discombobulated that it was hard to keep up with them. Son made all the arrangements and then mother called to change them. Then sister called to change what mother decided. Then we got into it by calling another sister to offer her a different room when we got a cancellation.
By the time they were due to arrive I was a basket case. They were some of the nicest people we have ever met and one of them got an Emmy for directing his TV show...Lost.
People at the door? Snap decisions. I like them or I don't (like the pajama-clad dog lady). I wish I could tell you what it is that raises the antennae but I can't. It's just a sense that something is off. Like a picture on the wall that is crooked. A perfectly clean room and then you notice a tissue in the corner or, more subtly, a crooked pillow.