User blog comment:KamiOfWind/Just so you know I am alive.../@comment-15745299-20141118234915/@comment-5294711-20141119083410

To clarify "ugly":

1. JPGs don't support the alpha channel, which controls pixels' transparency. Thus, every part of a JPG image is completely opaque.

2. JPG images are more noisy (this type of noise is also specifically known as "JPG artifacts") than PNGs or other higher-quality formats.

3. JPG doesn't truly support every color. Thus, the colors in a JPG images are more bland and less saturated (unintentionally) than PNG.