So far i like chili's and philbags... most.
Gawsh

Make a feller get all embarrased
Hey cool.

"Must spread some reputation around before...."
What he said
Lol. Isn't starting with good sounds the whole point? Mixing shouldn't be a pull your hair out experience. You shouldn't have to a shit ton of corrective processing. There's plenty of room for experimentation with these tracks. Use your imagination.
Actually, I reckon that (1) a true test of skill, and (2) a great way to learn a lesson, is to have to REALLY give it your all.
*cue SouthSide Glen style post*
For example, the Leaving Certificate (or equivalent in UK, USA, Canada etc.). We were told all that year that we were in competition with the thousands of other leaving cert students, and we were. It's a very tough time in anyones life (well, the people who give a shit), and so much effort goes into it. My girlfriend's doing the exams now, and boy is she stressed

Those who do the most work, will reap the benefits and come out on top, and vica versa. They'll get the best college courses, have the best looking LC results on their CV's when applying for jobs, so in a way they've kind-of "won the competition".
However, if it weren't a competition, and it was just to see who's actually competent and who's retarded, the exam would be much simpler. Maths is a mandatory subject, but since I left school I don't recall once having to figure out the hypotenuse of a triangle to get by in my daily life

It's made harder to "separate the men from the boys". Which is relative to what I'm saying about this mix contest. I just think it should've been harder: Lower quality recordings that don't mix themselves.
And, about learning lessons (about mixing). You'll never learn a lesson better than learning the hard way. Sure, it's not preferable, but it has it's benefits in retrospect. For example, I'm one of the few that kind of ran ahead of the pack in my class in college. I produced one of the best mixes out of the 30 or 40 other guys and girls in there, and I honestly credit it to starting out straight away at the end of 2008. I started recording my own stuff at home, and given the fact that I hadn't a clue what I was doing, they were terrible. I spent so much time trying to polish turds that I learnt so much more about what I was doing, and how to do it. Now, when I get good recordings to work with, it's a pleasure rather than a pain, and I get it done a lot quicker. I'd say it took me 45 minutes to an hour to mix Texas Terror.
Apart from the circumstances of a mix competition, or beginning to learn about mixing, then yes: it's ideal to have good recordings. The less you have to do to get it to "fit", the more time you get to be creative and make it kick ass.