The category is broad and includes genuinely useful educators. What defines it is the business model: attention is the product, and attention rewards confidence, dramatic results, and volume rather than accuracy.
The structural problems are worth knowing. Results shown are selected, the incentive is to sell access rather than to trade, promotional relationships with brokers and prop firms are often undisclosed, and the audience is drawn from people least able to evaluate the claims. Several jurisdictions now require disclosure of paid promotion, and in many places giving personalised investment advice without authorisation is illegal.
Assess them the way you would any other information source: full track record including losers, disclosed incentives, a method that can be described and tested, and behaviour when wrong. See parasocial-guru and shill.
Related: parasocial-guru, shill, authority-bias, survivorship-bias-in-advice