First, this question cannot be answered absolutely. In other words, it is not all reliable, and it is not all without music.

Theoretically, there is no free lunch. Free training, should be based on the content of its training, to determine the source of its profits and the rationality of profits. If its profit source is unreasonable, it is unreliable free training. For example, the free training organized by MLM institutions, whose profit source is the fees that attract people to pay, does not create value for society and customers or has no specific customers at all, is a Ponzi scheme.

Some free trainings in various legal coats and even tall packaging claim to have a so-called ZF background, and many leaders take photos. If the profit source is only the initial fee and there are no specific customers, it is not essentially different from pyramid schemes.