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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.

I think you mean proof-reading. This is totally different thing from peer-reviewing. The peer-reviewing process refers to academics and experts in your fields giving you scientific feedback. This is usually offered through conferences, symposiums, and journals. Anything else is suspicious and you should not go for. While proof-reading is editorial feedback (grammar, spelling, etc.). It is up to your institutions rule whether to allow third-party proof-reading or not. You should look into your institution's rules. There are some who define what a proof-reader can/can not do, while some institutions prohibit this specially for students.

UPDATE:
It is clear to me that you mean peer-reviews. As I said, this is suspicious. Respectful academics who can give useful review provide this service throgh known channels: conferences, journals, symposiums, etc.
Also, these channels ask these reviewers to confirm they will not disclose your work and they treat it confidentially. Other channels can disclose your work especially if you do not know the committee and if they do not have reputation to care about.

My advise: about my self, I will stay away from such shady channels. I only submit to legitimate known channels with clearly defined committee and rules. If something went wrong, there is a chair I can talk to. Otherwise you may find yourself in troubles.