As a reviewer, in addition to substantive comments and suggestions, I also include light copyediting. But sometimes a paper is so poorly written it becomes a challenge to evaluate the research. It seems unfair to outright reject... but I need it re-written. What would do you do?
@CatherineTan I list a few examples to give the editor an idea, and suggest that the authors seek professional copyediting if they can.

@CatherineTan

Quoted directly from a review I submitted before the holidays:

"""
Overall, I find it impossible to evaluate the study, given the current presentation. It may be that it could be improved in a way that would make it possible to judge the suitability of the study for publication. Comments that follow are intended to help steer in that direction.
"""

And then give some details about what you need to see in order to comment on the merits.