Starbucks and Whole Foods Market, known for eco-friendliness, signal their sustainability using a green logo as a particularly strong signal indicating socially desirable business practices (e.g., Mazar & Zhong, 2010; Yoon & Oh, 2016). Ironically, however, BP, infamous for the deadly and destructive Deepwater Horizon oil spill in the Gulf of Mexico, adopted a green label to counter the damage to the brand. Does the use of green to advertise environmental friendliness actually enhance advertising effectiveness? Do green strategies work if they are perceived to inappropriate? In contrast, does the use of grey-a colour that often symbolizes environmental destructiondamage brand images? Might success or failure of colour strategies depend on consumer scepticism about marketing persuasion? How do colours and words jointly shape consumer thought and action in response to sustainable marketing? Surprisingly, those questions have been rarely studied empirically. This research aims to fill the gap. Many advertising campaigns use visual elements as cues to enhance brand perceptions (Parguel, Benoit-Moreau, & Russell, 2015). Green is the ubiquitous visual cue used to trigger implicit ecological inferences in green advertising, but green can be abused through greenwashing practices intended to mislead consumers (Schmuck, Matthes, & Naderer, 2018). In response, the U.S. Patent and Trademark Office established guidelines to prevent environmentally destructive companies from using the word green in their trademarks (Collen, 2012). Theoretically, the current research proposes that marketing communications may be persuasive when colours are appropriate for the message, but inappropriate colour themes may cause resistance (Seo & Scammon, 2017). Accordingly, the persuasion knowledge model (Friestad & Wright, 1994) warns that if message recipients are explicitly aware that companies are using colour inappropriately to manipulate them, the persuasive intent may backfire.