@Randy572
With local guests, I would consider the length of stay. A local who wants to book for just one or two nights is quite possibly planning a party or some other event. I would definitely be asking this guest a lot of questions before accepting their booking.
However, someone booking for a couple of weeks or even a month (if you accept long stays) could be waiting for a house purchase to go through or a rental apartment to become available. I have often had foreign students who have just finished their degrees so no longer have student accommodation, but want to spend a bit of time enjoying London before heading home. There can be many valid reasons. Most guests will offer this information when they contact you and, if they don't, then I will ask.