Eater ran an article today including photos of several national food critics. Anonymity seems to be quite a big deal when it comes to food critiquing - the notion being, I suppose, that you want the authentic experience, not the special, for company version. That said, the NY Times' Frank Bruni was not especially anonymous, and he seemed to do pretty well!
I agree that it's probably best for a food critic to not flaunt their photo, but I'm not sure I think it's really that big of a deal. Personally, I find it kind of hilarious the extent to which some food bloggers -- not major journalists -- go to hide their faces. In a day and age when a bad review is just a yelp away, I don't imagine that restaurants only save their good stuff for the big reviewers. If you lavish attention on me, I might unwittingly write you a good review you didn't deserve, but someone else is just as likely to bash you.
All of that said, I am not going to hide all pictures of me online simply because I'm an unpaid food blogger. If someone is that interested, I'm sure they can figure out what I look like, but I can't even imagine anyone would care! Given how lucrative TV gigs are for "personalities" these days, you'd be a fool to avoid self-promotion opportunities just to avoid showing your face. Yeah, yeah, journalistic ethics, blah blah blah - journalists aren't paid well and newspapers and magazines are struggling like crazy. I say do whatever you can to be able to succeed in this biz as long as you do your best to give a fair depiction of the restaurants you review.
So here's my promise - I do my best to judge restaurants fairly. At least for now, I have no intention of publishing my own photo on this site. But seriously, I walk in with a giant camera. I'm not exactly dining with the stealth of a ninja!