It's not always that a property is in disrepair. We have been most successful picking up probate properties or properties sold as a result of a death in the family. 9 times out of 10, you'll find that the kids don't want to deal with the stress/headaches that they saw their parent go through and choose to sell it instead.
I had a friend who had a client who was going through a divorce and sold two income properties to buy a nice home.
Maybe someone found an up-leg property that is just that good that they need to get out of their current property.
You might also find that some people decide that they are far too busy and you might give them a number that is leaps and bounds higher than they could have ever imagined even if it is still a smoking deal for you. People who have owned their homes a long time are rarely aware of the appreciation.
I would be less concerned about why someone is selling and instead work on volume. If you want to be a wholesaler, think of yourself as a real estate agent. You're more or less a matchmaker and you're taking a commission in the process. Now, I'm not so sure about wholesaling. However, as a real estate agent, they recommend starting with about 500 homes. Typically it's a manageable number per expenses and provides ample opportunity to become a recognizable name. Just a thought.