Brand ambassadors do not really need to know everything about what they advertise or use same. Companies and businesses pay them because of their audience... people that will know about the business or product through their platform.
I disagree with this.
If you're a brand ambassador you should know what you're being an ambassador of. You are an ambassador of that brand. You know what an ambassador is right?
You're a corporate representative. You're like the public face of the company or brand so it will be very foolish not to know what it is you're a fact of.
It might be possible that you don't know the nitty-gritty of the whole thing, but you should know enough to know if it's a good brand/company or not.
Lionel Messi advertising a particular drink does not mean he must be a consumer of the drink... he is just paid to tell you that such drink exists and how fine the drink is. You are only required to check if you like and need what they advertised or not. No one will force you to buy what you don't have need of.
He doesn't have to be a consumer but he should be able to know that the drink is what they say it is.
Imagine being the face of an energy drink when in fact the drink isn't an energy drink. They just use your face for marketing strategy.
People like Messi should have their team check out those brands or companies before accepting deals from them.
Big celebrities shouldn't even be promoting what they have no idea about. Aside from the fact that they could be complicit in deceiving people knowingly or unknowingly, it's bad for their image.
Secondly, they can never lack deals, so why rush to take every available deal as far as the cheque is big?
I can excuse small and upcoming celebrities and influencers because they're just trying to get money but the already-made celebrities have no excuse.