Strange but has to be done.
When you make yourself a coffee or a tea, and your partner/friend/colleague/whoever makes one for you, does it taste wildly different?
I made myself a coffee this morning, lovely stuff, and he's just made me one and it doesn't even taste vaguely similar. I asked how he'd made it, order of things, and it was the same as I do it, but it tastes nothing like it.