I would look at the reputation of the publisher. Some are published by a reputable university. Those are likely to be of quality.
We must ask how is the textbook being funded. Authors put a considerable amount of work into writing a textbook, and need compensation. Where is that money coming from?
One source is grants. Government grants to fund a reduction in college cost is a possibility. The concern being addressed is that textbooks have become so costly they are preventing many from access to a college education.
Still, authors who write popular textbooks expect to have a revenue stream from royalties. Writing an open educational resource textbook will not generate royalties, rather there will be a one-time payment. Is this driving good authors away from writing textbooks? Time will tell, but logic dictates there would likely be a reduction in good authors as writing becomes less lucrative. Of course so there is an assurance of the payment is there regardless of whether anyone selects the book, so there is always a compensation, unlike a royalty undertaking.