Many shoppers do claim a tax deduction for the gold conferences. This of course would be against the Schedule C income of their business. There are IRS guidelines to be followed in terms of claiming accommodations, meals while in attendance, registration costs etc. I believe registration was about $100, you may be able to share accommodations with another shopper to cut that cost, but you still will have transportation costs. If you are considering it, do read the IRS guidelines first because things such as staying over to make it a mini-vacation or being joined by a spouse can reduce or eliminate the tax deductibility.
Reports I have read over the years indicated that the material presented was unenlightening. What they found made it worthwhile was meeting schedulers and other shoppers. Then there were comments about only a few schedulers appearing and of course that contact is useless if it is a company that has no shops in your area. Of late the comments have been that the shoppers who were there were all beginners looking for more hand holding through having a certificate to wave.
The MSPA provides their gold certification now by CD self study. It has been available about a year and I have heard of only one or two people who purchased it for the same $100 they would have spent for registration at conferences. I heard one say she had failed the test first pass but if I recall correctly you get 3 attempts to pass. I have heard nothing since then. I would assume that the CD would be tax deductible as would any other software or reference book which you purchased and in that same kind of category.
Certification is NOT necessary, as your son discovered. Your experience of his seeing the same jobs you are seeing confirms what I have heard before. We had a big laugh not too long ago when a really cheap job that most shoppers would take only if they had a route going right by the place announced that it was for gold shoppers only. A few days later they dropped that requirement and still had trouble filling it. I never checked to see if it went to bonuses to fill but it certainly was the kind of job and fee that would have needed bonuses.
Going to conference unless it is right in your backyard is likely to cost you $500 or more. That is a whole lot of gas shops to pay for the 'privilege'.