There’s some good news and bad news. First, it is common for counselors to talk with adcoms. Most top schools send their adcoms out around the country each year to keep in touch with local HS counselors. As Stanford says “College counselors from high schools all over the world are our professional colleagues. We rely on you to assist us in recruiting, evaluating and selecting candidates for Stanford.” Not only do they have annual meetings, they make it easy for counselors to contact them and its clear they expect to be contacted.
Around the country there are HS counselors that have been working with adcoms in selective colleges for 10, 20, even more years. They know and respect each other. The goal of the HS counselor isn’t to “get” some unqualified kid into a school; if someone tried to pull that the HS would be blackballed not only at that college but at many others; adcoms know each other, and stories about “what that counselor at Portola tried” are part of the chat at college fairs. Rather it is to help the colleges understand the applicants. In part this can be explaining the back-story; the kid with had a slip in grades because his mom has been in the hospital, the kid that doesn’t test well but who’s teachers swear she’s one of the best kids they’ve ever taught.
Which brings us to the less happy news. Like many kids around the country, you’re probably content to do well in class and haven’t needed a lot of counselor advice. Which is just as well, since at many publics there may be 1 counselor for hundreds of students and their time is spent trying to keep the delinquents in school. At many publics the GC’s don’t attend the adcom meetings, don’t see many kids apply to top schools, don’t initiate contact with the adcoms. So perhaps having your GC call isn’t going to do you much good BUT you don’t know that yet.
Make an appt and find out if your GC has contacted adcoms at selective schools in the past. You may be pleasantly surprised, and the GC can help out by finding out if there are concerns regarding your app. Again, not that the counselor can “pave them over” but perhaps there is more info that can be given to help them reach a decision.
To be honest, though, I wouldn’t put a lot of hope in this although you have nothing to lose by trying.