Pre-submission peer review services There are many websites offering pre-submission review services for a fee of several hunderd dollars, e.g., editage, editeon, enago and others.

In general this seems like a useful service - instead of waiting several months to get feedback from the journal referees (and probably a rejection), the author receives feedback after a week, and can then improve the paper and submit to the journal.

However, just like there are predatory journals, it is reasonable to fear that there are "predatory review services", that take your money and produce a worthless review.

So, my question is: what is a way to detect a good pre-submission peer-review service, and distinguish it from a predatory one?
The pre-submission peer review seems to cost about $250 USD for a one week turn around. That is not enough money to find an expert in the field to do the review. It is enough money to get someone familiar with the publishing process in a general field (e.g., biomedical research, engineering, humanities) who knows the core components of a paper (i.e., do you need to include statistics, do the methods seem reasonable, is there an introduction that at least pretends to make sense) and can follow a logical argument. Lots of papers get rejected for these reasons so such a review can be valuable. This is especially true if you do not have any colleagues you can pass the paper by. That said, you would be much better served developing a network of colleagues who you can pass a manuscript by prior to submission then to use one of these services.

Prior to using the service, I would ask to see a previous sample of their work. Unlike a predatory journal, which makes publishing somewhere else difficult, using one of these services only costs you money.