Advertisement is an art unto itself - you want to be visible, and you want people to hear about your things, but you don't want to get on their nerves too much. (At least I don't, as I feel annoyed sometimes by too much explanations of how good something is... and I don't want to be that seller.)
Ads can be an art themselves, too, and especially older ads are quite interesting to look at. They do reflect the time they were made in, and sometimes they look weird and funny to our eyes, with different backgrounds and different lifestyles. And, in some cases, a bit more knowledge about what might be a good idea and what might not be one. (Radioactive potions, anyone?)
In case you, like me, enjoy looking at old ads once in a while, the Internet Archive has you covered. Here's their selection of advertising art from magazines. Enjoy!