It's easy to identify them:

1. Clients with Unreasonable Demands: Look for clients who demand excessive skills or experience but offer low budgets that don't match the expectations.

And this is exactly what is happening there: the client wants an expert for a hundred bucks! I've just seen some like him...

2. Negative or Vague Client Feedback: Review the client's feedback to assess their history with previous freelancers. Negative or vague feedback may be a red flag.

And he has some negative feedback. That's the point.