I'm guessing you don't do this kind of work on an enterprise level on any regular basis, correct?
I sure see this a lot on forums and it really bugs me. Some one posts a "I'm a professional such-and-such, therefore my opinion is more valuable." type post. Some replies and says, "Well, I'm a professional such-and-such too, but my opinion is different than yours." The the first person comes back and says "Well, you must just be a kid playing around because you couldn't possibly know what you're doing and think that." I'm not sure it's what you mean, but you come off as an arrogant know-it-all and nobody is going to be particularly receptive to your argument because of that. Argue based on the merits of your argument. Don't simply appeal to your (dubious) authority especially if you're going to discount someone else's without any real evidence to back your position up.