This is scientifically proven to be a losing proposition. Every study on this issue shows that humans remember negative stimuli far more than positive stimuli.
That said, that does not mean an effort shouldn't be made to attempt to offset this. For example, one way that I believe might help some people on this would be of the product supported some sort of hypothetical online dice rolling app that was coded to work for all sorts of apps like D&D, craps, monopoly, etc.
It would be rather more difficult to suggest that such a product neutral app could possibly be cheating. It could show a log of the rolls so that people couldn't argue that gnubg just claims to connect to it bit either does not or simply changes the rolls after the fact.
Telling someone to roll their own dice doesn't work because it's too time consuming whereas connecting to a dice app takes only minutely more time than normal.