There are no rules, all labels differ, some will float off with hot water, some can be peeled off if you fill the bottle with hot water and keep the label dry.
With many others, you may manage to scrape all the paper off but will then have to use scourers and/or solvents to try to shift the glue.
And then there are some which are attached with the same stuff that NASA use for fixing the heat tiles to the shuttle.
Trouble is, you can never tell which is which.
Bottles are free, if a label is being stubborn, chuck that bottle back in the recycling and move onto the next.