Some are certainly predatory but are disguised in such a way that they appear to be legitimate. Hence my question.There are of course plenty of legitimate conferences, even if they are not terribly well known, e.g. The International conferences of the Asia Association of Computer Assisted Language Learning (AsiaCALL) of which I am the current president so... Laverne, come and join us. :)
A legit conference website will have a professional look. Check their contact details, emails and all other contents from their website. Do you find any bad English, or misspelled keywords or improper jargon in your field? If the answers are Yes, then it might be a scam.