I dislike when questions are worded like that, because it could be interpreted in two ways:
a) Given an arbitrary case, is there a chance that modifying commits is considered a poor practise in that case?
b) Is the belief that modifying commits is poor practise held by the population at large?
The answer to a) is yes, the answer to b) is no.
Some people prefer a clean history, where you have to explicitly request the steps to get to it if you want them. Others want the messy steps to be part of the history you show up-front.
