Sorry, I dont have any 'professional credentials', but I DO have 3 Megatraveller books chock full of corrections due to typos. I stopped doing it for TNE because it made it hard to read, and I pretty much had to read the T4 book in groups of 2-4 pages so I didn't go nuts and cover the thing with ink.
On the other hand, Word has a handy little feature that allows some one to do proofreading, put in their suggested changes, untypos, and all that jazz, and makes it easy for the actual author to see what the changes were, and then he adopts whatever changes he so desires, or makes up new ones. Nifty, I think.
That supposes you're using Word instead of Acrobat. Anyway, I've done plenty of unofficial proofreading (I'd say 'unprofessional', but you'd get the wrong idea) over the years. I had two years of Journalism in high school, and basically wrote most of the school newspaper in that time. I also had a job at McDonald's for 6 months, and we all know how relevant THAT is. And I was in the navy for 6 years; that tells you I can handle or give orders, or more importantly, conduct sweepers.
But I offered mostly as a fan, not some one who does it for a living. (I've officially playtested a few games, and I can drop names for you if you think that helps you decide.)
