A agree that many are dubious (Jago did mine, took the idea and cloned it). I have had many famous 'clients' through my courses including Katherine Tate Gina Yashere, Marc Lucero, Joe Wilkinson, Dan Renton Skinner and many more. There is a rule of thirds - a third can do it (as listed) and they were already doing it when they came to me. A third can be taught - they have aptitude and some skill but need to know more about the techniques and how to hone their writing/persona/approach and marketing tips. For them a teacher can be very useful. They will, of course, ultimately learn it on the circuit, but a strong course is a good incentive. The last third are hobbyists (nothing wrong with that) Egotists (hmm) Time wasters and loonies. Creative courses always draw them in.
If you take a course you need to know that the tutor has done it, is doing it and knows his or her shit. I no longer teach Stand up, but I recommend Logan Murray, Jill Edwards, Sally Holloway and Rob Hitchmough, all of whom know what they are talking about.
Ultimately yes, it is a job (and it IS a job, not a career unless you are very lucky, talented or well connected) and you learn by doing, but it takes ten years to be any good. www.writingsitcom.co.uk