Advertising projects false images. For example, some ads imply that you're not cool unless you drive an expensive car, that smoking means you're an independent spirit, or that to be mature means drinking alcohol. Commercialism contributes to environmental problems by encouraging wasteful use of natural resources. Over-packaging, disposable goods, and buying things we don't really need all contribute to unnecessary use of limited resources. The manufacture and disposal of the things we buy cause other environmental problems, including habitat loss and increased air and water pollution.
Billboards cause visual pollution.
Advertising perpetuates stereotypes. Advertisers influence the content of publications and broadcasts. Government censorship of the media is illegal. Yet it is well documented that newspapers and other media are censored by advertisers. For example, a beer producer may pressure a magazine in which it buys ad space not to print articles on the dangers of drinking.