It certainly depends on the opportunity. Obviously if there's a commission only sales role with an easy-to-sell product, large commission earnings and generally top notch potential, other base salary + commission jobs could look much less appealing by comparison. But that potential needs to be good enough to mitigate any feelings of the employer only doing it to take advantage and avoid risk.
By and large though, they are not very common and, as you say, tend to be very picky. Unless the OP is offering a fantastic opportunity to earn serious money in a quality niche (which is also rare), good sales people are likely to want some security (or may not even want the job at all).
I agree with almost everything you say.
OP, you need to consider why you are not getting much interest, something in the offering is not working for the agents, so you are most likely flogging a dead horse.
How long is the normal sales process, hours, days, weeks, months?
How long would the agent have to wait until they could expect any income?
How much is the agent likely to have to risk, ie petrol, lost income, before getting cash flow positive?
Is the commission ongoing or a one off payment, retention and claw Backs?
How much can they reasonably expect to earn?
The hardest question I usually ask, and where 99% of such offerings die on the spot, how many sales have the management made individually in say the last six months?
The answer is usually 1-2, but they are not salespeople.
