Whether its Upwork, Guru, Freelancer or any other marketplace, bad clients abound in numbers and at this time, they probably even outnumber the good ones by a good margin!All kinds of treacherous things are being done which are giving a bad name to the noble profession of freelancing. There are those who take your credit card numbers or other information in the name of offering a job, those who try to extract free work from you and even those who try to get you registered on various services in order to complete their sales targets.You need to be vigilant and aware of these things round the clock. A rogue client not only dupes and deceives you, but has the potential of making you lose faith in the very profession of freelancing. One bad experience could be mind-numbing for a lot of freelancers. They lose faith in this profession and go back to their 9-5 jobs to never return. But only if they were a bit more vigilant and lucid about these things, only if they had handled that freelance project carefully, their future would have been so bright and they'd have accomplished their dream today.I'm going to list down some techniques which I frequently use to filter a new potential client when I meet them first time.The first thing you must do is weed out those who try to bargain heavily with you. Now, its quite possible that the potential solution you are offering is a bit overpriced and a discount could be offered but before making that offer, observe how they are bargaining or negotating. There is a behavioral difference between a client who genuinely wants just a fair discount on value, and another who wants to get everything done for nearly free. There is a vast difference between the two, the former still values your skills and is only debating on, whereas the latter simply treats you as an unneeded expense. With experience, it becomes easy to recognize the difference between these two types of clients.A good client or employer is typically liked by most freelancers or employees they've worked with, they'll write about their interaction with the client and how they felt working with them. Read as many reviews as possible and pick randomly because its easy to fake reviews these days. Also check reviews across all platforms, not just one like Upwork or Fiverr. If they are a new client and don't have any past review, you'll have to focus on the next two steps with more care.These days, almost everyone is on social media and many of them pour their entire life stories into it! Try to search that client on quora, twitter, facebook, linkedin, etc. and see what their public posts say. You'll get a good idea from that about the nature and authenticity of the client.Its not easy to judge human nature right from the first interaction, don't rush through your proposal and immediately say yes. Take your time and interact with them, ask a lot of questions (especially, if you didn't get what you're looking for in above two steps). Ask frankly about the project management tools you're going to use (github/trello/etc.), the way you're going to communicate (email/skype/jitsi/etc.), etc. If they make any demands, consider whether they're valid or not. An NDA is typically fine but if they ask you to register somewhere or ask you money, then DON'T DO IT. A client has no reason to ask a contractor for money, its as simple as that. And in the 0.001% probability that the client was indeed genuine, its still not worth taking the risk. Decline the offer and work on the next proposals.Proposals keep coming and going on your desk but such bad experiences have the potential to make you quit working on that desk, so understand these risks and always stay vigilant.