Irrelevant analogy that does not fit here. Unless the person with the best hair cut their own hair, it does NOT relate to a bodybuilder who spent years building their body up. You don't gain a shit load of muscle by someone handing it to you or "cutting your hair for you".
Gee, I would go to the person who had PROVEN they know what they are talking about BY PRODUCING RESULTS either in themselves or others. A beginner has done NONE of this.
It matters to a large degree both what they look like and what they have done. Unless that skinny personal trainer has personally prepared people to reach the level I am after, he has proven nothing about what he knows...so his own personal development would become that much more important.
A picture doesn't tell the WHOLE story, but you can guarantee it tells a great deal. There is very little I need to hear from some newb. An experienced personal trainer worth listening to will have a list of people with great physiques they either trained directly...or they will have built themselves up using the tactics they believe in.
Anyone else is largely not worth listening to if they have no results to show at all.