Some are good, some aren't. The problem is, a Bootcamp student can't tell the difference and there's nothing like an accreditation system for them so it's full on market for lemons[1].
This exactly. It reminds me of the "ESL certifications" you can get online - there's no presiding international body for guaranteeing some minimal level of quality / competency.
Well at least for those CEFR and TOEFL exist.
I should have been more clear. Those are for students who are learning, ESL is for people who intend to teach English. There are only two real recognized certificates for it - Trinity which is Oxford, and CELTA which is Cambridge.