If the idea is that a rater's "job" is to review courses, then presumably expenses paid to do that job would be deductible. More likely, in any sort of employer/employee relationship, the employer would reimburse the expenses, so the cost to the rater is already nil. Similarly, a food critic is almost certainly reimbursed by his/her employer for the cost of meals (taking comped meals is a bit of a no-no from what I understand). Or to take Michael Whittaker's example, if theater critics had to pay for their tickets, they would also deduct the cost of those tickets from their taxable income. So no, this isn't taxable income. It's been brought up in this thread (I think), but things that we may see as perks aren't actually characterized as such by the IRS. I like going to baseball games, but if I were a sports writer, I wouldn't expect to be taxed on the value of tickets that I didn't have to buy, and even if I were charged for entry, they would be deductible as a legitimate business expense.
Moreover, I have a hard time buying into the idea that comped rounds are compensation for services rendered when there is no guarantee of any services being rendered. I'm not a rater, but my understanding is that there's no expectation that EVERY round a rater plays must be submitted (and it would be difficult to police anyway). And while certainly a comped round at a club might entice me to review their course, there's nothing requiring me to do so. There's not even really an implied contract. And as Michael pointed out, there's just as good a chance that the review is counter to the club's interest rather than productive.
Full disclosure, I've been employed as a tax consultant for the last ten+ years, and I'm probably not the only one here. Though admittedly, while I've dabbled in a bit of everything, my area of expertise is sales and use tax.