There are cases where quality/perfection doesn´t matter that much or it would cost a disproportionate amount of money/time to get it perfect, and there are cases, where it makes sense.
If you publish blog articles, it´s not that important that it is 100%, if you publish a book of course it´s more important, and if you publish a book that´s going to be printed, it´s still more important obviously (but even in books that are printed and have gone through the hands of several proofreaders and editors, errors are found lol perfection really is hard to obtain).
Some people interestingly aren´t ready to invest a bit even into things that make them money right away like Amazon products other than books with real companies behind them and not ‘just’ an indie author.
Some of the English texts (translated from another language into English) I get are gruesome, I often recommend to get a native English proofreader (at least, sometimes a copy editor would be needed unless the proofreader doesn´t mind to re-write the whole thing under the label ‘proofreading’). I´m not sure if they think or know that people will order the products anyway, but since there are peope who are aware of quality, and look for sellers here who can deliver quality translations for such products as well, I´m inclined to think that those think and know that their products will sell better, if the text is correct and ‘trust inspiring’.
I´m not sure what to think when a professional Amazon seller doesn´t even want to spend 10$ on a proofreading+correcting/re-writing of their English text, when they are told that they really should - they’d only need to sell 1 piece more because of the better/correct/real English sounding text, and the costs would usually be more than recouped already, and I´m pretty sure there always is at least 1 potential buyer of no matter what kind of item who´ll click the next search result, when they see an obviously bad translated text - they´ll expect the product to match the text and won´t feel safe in the purchase as they’ll feel communication would be a problem in case there´d be a problem, if the seller doesn´t speak their language nor seems willing to pay someone to take care of that.
But I digress, I should write a blog or book or something on that some time.
Proofreading for a translation that was done well actually even could be a problem, in case the translator was good but the proofreader isn´t lol they might ‘correct’ things that were done on purpose . The ideal would be a proofreader who is a native speaker of the target language and speaks the source language very well too and would proofread with the source language on the left side and the target language on the right side of their monitor (or vice versa ;)) but that of course is again a question of available funds and available sellers.
But a proofreader or second opinion or re-translating to check and at least ‘avoid the worst’ is a good idea either way if it´s important and or one isn´t sure about the quality.
Maybe it would be a viable solution to ask a native speaker (translator, writer, proofeader, any native speaker with a good general education and command of their own language probably even in many cases) to just check a page or chapter (just long enough that they can read and comment on it for 5$ or whatever you´re wiling to spend on it), without actual proofreading or anything, and depending on what they say, you have peace of mind, or can find someone to fix it, if its too bad.
Some time ago I read a very interesting blogpost on the topic of perfection and errors and publishing blogs and books, as I had an order for a translation of that post into German, it might be an interesting and helpful read regarding your doubts, @gina_riley2, I don´t want to put the link here, but you can PM me for it, if you want.