The first red flag you’ll notice is in their email address. If you’re looking for breeders and the only contact information they provide you with is an e-mail address, it will most likely be a scammer. If there is no phone number, no social media, nothing but an email; you can know there’s something fishy going on. Also, if their website is not secure, then the source is most likely unreliable.  Of course, it's a red flag if the breeder doesn't have any form of registration or membership in any local or national cat registry.  Sometimes, breeders can be at the beginning or during some change in their business, but they should be able to provide you with concrete evidence and an explanation for this.