I'm doing some competitive link analysis for a new client in the food industry right now and I've come across one of their competitors using this tactic quite extensively, and it seems to be working very well. They crush their competitors as far as domain authority. Most of the anchor text is branded (company name) but you can quickly tell that there are one or two keyword phrases that they have targeted. I can only assume that they were getting some of the bloggers to include the custom anchor text. It's definitely not overdone, so the overall link profile still looks natural.
The bloggers that they're targeted all seem to have relatively authoritative sites which I can only assume means their brand is getting a lot of quality exposure on these sites as well as referral traffic. I'd hazard a guess that the direct referral traffic and overall exposure is worth as much or more than the increase in organic rankings that they would see because of these links. None of these links were nofollow or affiliate links.
The general rule of thumb I've always espoused (with a few exceptions) is that anything that you are doing for SEO purposes should have an equal or greater benefit to you for _non-SEO _reasons. I guess that's sort of my test to see if something can be considered a legitimate white hat technique. But there's obviously still some grey area with this.