Seagulls definatly are good at stealing things. I saw one take a plastic bagged sandwich out of an unzipped lunch bag that was only left unattended for about 3 seconds!
They do seem to like hotdogs. I started feeding a group of seagulls with tiny bits of hotdog and I almost had them eating out of my hand! I've fed pigeons out of my hand before. They got so close that my sister and I were petting them. Our brothers were laughing watching us and one of them said, "I bet you can't catch one." Immediately, my sister had caught one
I grabbed one of the pigeons too, but I didn't hold it's wings down so it got away.
When I lived in Jacksonville Florida, people were being arrested for putting bread on fishing hooks and using it to reel seagulls in, casting the lines into the air.