A survey conducted by corporate consulting firm Cone and the Boston College Center for Corporate Citizenship released in February found that only 47 percent of consumers trust the sincerity of businesses that push an environmentally-friendly agenda, USA Today reported Tuesday.

A new spate of green-oriented advertising also makes it harder for a company to stand out as eco-friendly.

"It is a good thing to do, but is anyone going to notice?" Allen Adamson, a marketing director at Landor Associates asked.

Corporate efforts to look green won't be noticed, "unless you do it in a big way and extend your efforts well beyond Earth Day," Adamson said.

Companies trying to appeal to environmentally conscious customers include the Las Vegas Monorail Co., which advertises itself as "zero-emissions transportation," and Kim and Scott's Gourmet Pretzels of Glenview, Ill., which says it will plant a tree for every person who signs up for membership in the "Pretzel Club."