• Unprofessional email addresses could be a red flag.
• Make it clear to your potential vacation rental guests, that they will have to accept your rental agreement (including house rules) in order to stay at your place.
• Ask your guests in the early exchanges, if they’re available for a quick call or instant message (phone, WhatsApp, FB Messenger etc.). It might be a warning sign, if they don’t want to talk to you.
• Increase your minimum stay length to three or four nights in order to discourage party animals who are looking for a cheap venue for a night.
• Setting a high damage deposit will help dissuade unsuitable guests to stay at your Vacation Rental.
• Do some online research and get a better idea of who they really are (Google, Facebook, LinkedIn etc.) …

(Source: via @Lodgify – https://www.lodgify.com/blog/screen-guests-outside-listing-sites/ )