The card More or Less, from Unstable, has the text:
Add or subtract 1 or one from a number or number word on target spell or permanent until end of turn.
If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.
I choose the number word "one" in the condition of the replacement effect to change the text from "if one or more" to "if zero or more".
When will this replacement effect apply? I know that when 0 damage would be dealt, the game treats that as no damage being dealt. But are there any rules that cover zero +1/+1 counters being placed? If not, conceivably I would put one +1/+1 on each creature I control each time a spell or ability doesn't put any +1/+1 counters on a creature I control. Is that really how it works?
And furthermore, if that's how it works, does the replacement effect only apply to spells and abilities, or are there other game objects that the replacement effect would apply to, so that I would need to put +1/+1 counters on my creatures at times I might not have expected?