First off - thank you!

Only rarely do I receive compliments on my appearance.
Your presumption that Freemasons are generally good-looking is probably the result of a sampling error. Most of us aren't drop-dead handsome. (although, I do admit, it doesn't detract from our appearance to wear a suit

) One's looks really are of no significance or consequence in Freemasonry.
We indeed are ambassadors of our fraternity at school, work, and society in general, but we like to think our character is our calling card. As Freemasons, we are taught to 'square our actions', which is to say we are enjoined in being virtuous, just, and honest men. Physical appearances are but transient - the ravages of age and mortality take their toll on the body.
If you fear that your looks will come in the way of your becoming a Freemason, rest assured that your fear is unfounded. As a Mason, all you need is a belief in a Supreme Being, and a good moral character. Your appearance really does not matter.