But that's not what's being sold. If the bullshots are created in-game, then they're not swapping one product for another like your example. It's more a case of seeing a Covette ZR1 for sale, advertised as 'a model sportscar' for $50, buying it, and finding it's a tiddly little model where you read 'model sportscar' to mean a pinnacle of design.
English is full of ambiguities as interpretations. It's no-one fault. People just have to make sure they understand where someone is coming from, rather than assuming everyone else uses the same meaning for words as oneself. I'll grant photomode shots can be unethical if the creators deliberately release photomode shots or tarted up non-game imagery knowing that the public will expect that to be in game without trying to educate them, but that's advertising the world over. We're lied to constantly, from businesses and politicians and so many others, bending the truth and manipulating language. It'd be nice if everyone was straight-up, but that's unlikely to happen as people compete (who here has stretched the truth on their CV for example...). It's better for people to learn and understand how things are and work out wehat's what themselves, until some cosmic event creates a truthful Utopia!
And in this case, just labelling something as 'in-engine' isn't IMO any form of untruthfulness. In most cases it's applied anyhow.