Why does there seem to be so much deception in advertising despite truth-in-advertising laws?

The consumer must be more proactive in fighting against deceptive advertising. Investigations start after numerous complaints are submitted by consumers to their local better business bureau. When there is a sufficient volume of complaints, the BBB will refer the matter to the Attorney General and/or FTC. However, most often the consumer just gets angry and does not complain. The result is that the behavior continues and often grows.

I think that Richard is right that most people police themselves and that the skeptical nature of our society takes the imagery we see in advertising with a large grain of salt. Truth in advertising laws relate to making sure that what you say is true to protect the consumer from being mislead or taken advantage of but as to your example that doesn't mean that the advertiser wouldn't want to show their product in the best light possible.

Yes, there are really truth-in-advertising laws.  There are also laws in each state against deceptive advertising (they often fall under the heading of consumer protection laws).  Your second question is a little trickier.  Enforcement often comes in two forms: (1) the government or (2) a private individual or company.  Government enforcement often comes when a consumer or competitor complains to the FTC or BBB/NAD.  In the second case, an individual or competitor may write a letter to the infringing company and demand they stop, and threaten specific government enforcement if they do not.  In my experience, this is sufficient to accomplish the goal. Lastly, the role of Social Media can be a powerful enforcement tool.  When consumer complain, it can create a viral campaign that cannot be controlled by the advertiser.  This alone can be enough to discourage a company from falsely advertising its products or services.