You Have My Word On It!

There's an advertising campaign that runs in the Columbus, Ohio market that never fails to irk me. It's from Speedway, which is a chain of convenience stores that also sell gasoline. During their television spots, they promote the food products they sell inside the marts. In closing, some sincere looking, fresh faced 20-something store employee or manager promises that consumers can expect a particular item at a specific, appealing price point, beaming, "You have my word on it!"
  
I have nothing at all against these young people (I'd have the same reaction if it were a person of any age) but why is that this message is not especially impactful to me? Could it be that I have no reason to believe that these persons' promises carry any particular weight?Perhaps, if Speedway provided us with some reason that this promise was somehow meaningful, it might influence me to visit their store (probably not, but I'm trying to make a point here). Again, it's not the messenger, it's the message. It just isn't compelling to me. 
 
This brings me to the topic of "reasons to believe" (RTB) in consumer marketing messages. RTB's are the expressed support for the promises that are being made. Claims without credible support often aren't believable. For instance, Listerine Antiseptic Mouthwash is effective at promoting good oral hygiene, because (per its website):
it has been proven in clinical testing to remove 21% more gingivitis and 52% more plaque than brushing and flossing alone. This, combined with (at least in the case of Original Flavor) a harsh taste that is consistent with aesthetic expectations for an antiseptic product, convinces consumers that it is effective.
 
On the other hand, products that don't explain why they work, or don't offer compelling reasons to believe are troubling to me. Just hearing former game show host Chuck Woolery tell me that an arthritis pain relief product works great, without any further assurance of effectiveness beyond a money back guarantee is hardly a convincing message. http://www.australiandream.com/welcome-chuck
 
In summary, credible, compelling and well-substantiated RTB's are an essential part of any product sell message. Consumers are most definitely listening for these pieces of information to build their confidence in making their purchase decisions. Marketers who think otherwise, do so at their own risk. 
 
What are your thoughts?