In xkcd style...
JPEG isn't always right. If you are one of those people who just assumes JPEGs rule the world and make all images JPEG, please stop. There is a time and a place where you have to put the JPEG encoder down. It's not a silver bullet.
I've seen a whole slew of web comics using JPEGs. Not good. Sometimes I see things by supposed technology websites that make me want to cry. Seems to me that if you are using the web to publish things, you should know what you are doing. You should care about making them look correct. Maybe they have their reasons. Maybe they want to save to bandwidth while making their graphics look trashy.
Maybe no one notices but me.