Honestly, this sounds like a great idea for a forum activity. At the same time though it is pointless and senseless. If it is a cook off, the basis of judgment is looks, presentation, and most important of all taste. Doing this contest online will defeat the purpose of it being a cook off. Any member can just buy good looking ingredients and garnishes and decorate their plate accordingly to make it look good for judgment. Though that is the only way this event is feasible to do online, you are forgetting the main factor which is taste. No matter how good you decorate or make your dish look elegant, if it doesn't taste good then it's no good. The opposite is also true with this, a talented member could have cooked a great meal, but due to the fact he doesn't have a camera to make his dish look presentable as a JPEG picture he/she will loose to the one who has a better camera and better decorative skills. Once again disregarding the main factor which is taste.
you do realize that plenty of cooking forums do these kinds of contests all the time?
if you're gullible maybe you will think some seared salmon with a tomato rose and a lettuce leaf on top is some culinary masterpiece compared to a perfectly cooked shepherd's pie but ideally the judges would take that into account.
it's easy to make food look appealing but if you didn't do anything or what you did was shit, or if you clearly undercooked something and idk sauced it over; they will be able to tell.
example:

presentationwise, not much to look at. it's sloppy, the lighting is awful, there's a grain of bread on the mat, spilled wine, a terrible looking wine anyways, and it all looks like a mess.

the lighting here is great, the chicken is well presented, and the sauce looks hearty. if I hadn't started eating, that little smear wouldn't be there.
by presentation, number 2 clearly wins.
except number 2 is just some ragu mixed with wine, two fucking types of pasta (if you just looked over it you probably missed that (also if you think that is culinary sense you're nuts)) and a bit of leftover chicken, and number 1 was a complicated homemade vodka sauce with organic spaghetti and pan cooked chicken. by reading the ingredients alone, its obvious which took more work and which probably tasted better (answer: number 1). I've also made better looking dishes that were shrimp marinated in mountain dew and beans stirfried in coke, and they tasted like you'd expect (SHIT), but looked interesting.
so what you expect from a competition like this is this!

beautifully cooked shrimp, a nice thick scampi sauce (thanks to some white wine I mixed in which gave it an interesting fruity kick), just a bit of visible seasoning. appealing, but not in your face gauche. good tasting, but not at the sacrifice of looks.
and yes, I am trying to psyche out my opponents hehehehehe IF I HAD TAKEN A PICTURE OF THAT ORANGE CHICKEN I MADE Y'ALL WOULD BE SHITTIN YO SELVES.