In my experience, if people say they used genAI they're probably telling the truth unless the thing they're trying to convince you that they used genAI to make it is impressive in any way.
If they say they only used genAI a little bit that means the entire thing was shat out by genAI unless it's something like botnik where it's performance art driven by genAI (markov chains) being useless.
If they say there's no AI in it, it's like 1/10 odds that it's completely genAI and 9/10 odds that they're telling the truth.
@ben The phrase is also used to divert blame for the bad thing onto the machine, away from the operator of the machine.