Will color make you drink more?

Pepsi is in the process of revamping their logos for their major beverage brands to struggle back from drooping sales. It's interesting to consider that a redesign, or refreshed color scheme, could encourage people to chose their drinks over competition's.
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No official pictures to post as of this posting, but we've got this rendering as a teaser. The new logos will loosely form a series of smiles. A “smile” will characterize brand Pepsi, while a “grin” is used for Diet Pepsi and a “laugh” is used for Pepsi Max (s0urce) What do you think? An improvement, or big mistake?

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When Canada Dry’s sugar–free ginger ale can was changed from red to green and white, sales went up more than 25%. The red can had evidently sent a misleading cola message to consumers. (source)
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M&M's wanted to roll out a transformation of their M&M's brand, so instead of quietly making the change, they turned it into a major promotional opportunity, calling it the "Great Color Quest".
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The new M&M's would have more vibrant colors and the M's would be printed larger (the first logo change in 60 years). So instead of just advertising a make-over, the marketers took the colors away so that the consumers would notice the new colors.
"By involving consumers in the process of reclaiming color through a nationwide contest, we've made the brand transformation into a fun and interactive process, and by taking color away from M&M'S®, we've demonstrated just how important it is to have it back." (source)
I find it fascinating that marketing can be that manipulative in terms of boosting sales simply by swapping out colors, or tweaking designs just a tad. Are we, as a consumer society, that easily persuaded by marketing?