What Do You Look for When Evaluating Research Peptide Suppliers?

I've been spending some time learning about research peptides, and one thing that keeps coming up is how difficult it can be to evaluate suppliers.

On the surface, most companies seem to make very similar claims. They talk about quality control, third-party testing, transparency, purity, customer service, and fast shipping.

The challenge is figuring out which of those claims actually mean something and which are mostly marketing.

For those who have spent a lot of time researching peptide suppliers, what factors do you pay attention to when evaluating a company?

Do you focus on things like Certificates of Analysis, independent testing, transparency around sourcing and manufacturing, customer reviews, community reputation, or something else entirely?

I'm not looking for specific supplier recommendations as much as I'm interested in understanding the process people use to determine whether a company is worth considering in the first place.

What has proven to be the most reliable indicator of trustworthiness in your experience?