How we change what others think, feel, believe and do
Accuse them of having some hidden agenda or ulterior motive for what they are saying or doing. Make the fact of this deception such an important and terrible point that you can dismiss their entire argument.
Accuse them of trying to control you. Say they are trying to pull the wool over your eyes but you can see what they are doing. Say you have information about this.
Bring others in on this. Create a 'conspiracy theory' that explains why you are not being told about suspected bad things that are going on behind closed doors.
You would say that. All you really want is to sell it to us. How can we know you are telling the truth?
Well that would benefit your department of course, but what about the rest of us?
I think there's something here that you're not telling us. What was going on at the lab meeting, eh? I heard something about that. Come on. We're not stupid.
When people are trying to persuade you, they seldom do it for solely altruistic reasons. Everyone knows this and so it makes sense to question other motives, especially if they are framing the argument as 'good for you' and with no benefit to them.
Children often use this argument when resisting their parents attempts to control their outlandish actions, arguing that their parents are unreasonably seeking to control them for no other purpose than to maintain 'power'. The same accusation may also appear in arguments between romantic couples.
In business and other organizations, people often seek power and quiet battles can rage in the board room and elsewhere. In such contexts it is easy to suspect people of lining their own pockets or acquiring power through ongoing persuasion and change. The 'grapevine' may well be full of such stories you can use.