I guess it is more of an art than a science.
Couple of generic points (and these are guides rather than set in stone)
* Good people work with good people.
* Good people tend not to boast
* Good people are willing to say they can't do something or that it would be a challenge for them
* Good people are specific in what they want
* Good people tend to have longer stints in each company
On top of that I have been in the civil engineering space for a long time. And while I couldn't design or build a bridge I can hold a conversation about what is involved in doing it. So when someone is talking to me I can get a feel for if I am being spun a line or not.
Finally, after 10 years in the same market I am close friends with a number of the managers in the consultancies and have long working relationships with many more. One of them will know you or of you.
I normally don't post about work on here so try to keep it separate - send an email to harlequin80@mailinator.com and I will email you directly with my contact details.