I had a fellow approach me at a model contest as I was putting a model down on the table. His first words were, 'That's painted the wrong color', to which I replied, "What's that smell? Is that YOU?" It ended the conversation rather quickly, thankfully.
Gil nailed it on the head. I've had people tell me not to buy a model because the nose was 1/64 of an inch too long, or that the cockpit floor was too shallow. The only ones I listen to are the people that tell me I can get it for $25 less somewhere else, or if the kit is unbuildable (some of that Eastern European stuff from the late 80's, early 90s...sheesh).
I've built kits and scratchbuilt models for museums, private collectors, and even major defense contractors. Unless it's blatantly wrong, 99.9% of the people who look at aren't going to know if that's a Revi 16 or 14 gunsight, or if that particular version of P-51 had smooth or diamond tread tires.
Build it and have fun doing it. When it stops being fun, its time for a new hobby.
Jeff