It simply comes down to the colour of the bud, if you look you can see it's more of a grey/brown tone, this would give us as viewers online the initial 'warning signal', ideally it should then be followed up by a closer inspection by the grower, you can sometimes see what looks like 'fluff' or very fine hairs bundled together inside there too on affected areas (when checking in person).How do you identify bud rot from that picture? Honestly asking. What are the "clues" that led you to that conclusion?