Second pass at: Identical chromatograms across two different lots posts 31–60

Pricing patterns: unusually low prices for what are otherwise consistent with market rates might indicate lower quality, stolen goods, or a scam. Unusually high prices without justification raise different flags.

Worth separating two things that post #42 runs together.

Exaggerated claims without documentation: every compound has limits. No peptide is "100% pure" because purity is measured to finite precision. A supplier claiming implausible perfection without backing evidence is overreaching.

For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.

Evasion when asked: if a supplier does not clarify when asked specifically for method details, counter-ion form, or batch origin, that itself is a red flag worth documenting.

post #48 answers the question as asked. The question underneath it is different.

I disagree with the reply above, and I think the disagreement is substantive rather than terminological.

The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.

On post #46 — agreed on the reasoning, with one qualification.

Inability to trace lots: if you ask "where was this synthesised, by whom, under what conditions" and cannot get a clear answer, that is a red flag. Traceability is not glamorous but it is foundational.

Patterns that reliably precede a problem: underdosing (less active material than stated, documented by independent testing), mislabelling (wrong compound, wrong strength, or wrong batch on the label), and failure to provide documentation when asked.

Rapid supplier turnover: a supplier that changes corporate structure, domain name, or contact repeatedly in short time windows raises suspicion about stability and legitimacy.

I disagree with the reply above, and I think the disagreement is substantive rather than terminological.

The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.

Coming back to post #53, because the follow-up matters more than the original answer.

Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.

The correction was fair and I had been repeating something I had not checked carefully enough.

Picking up post #53: that is the part I would want checked first.

Unresponsiveness: a supplier that does not reply to reasonable requests for documentation or clarification is showing you something about how they operate.

Safety documentation absent: a supplier that cannot provide information about sterility testing, endotoxin testing, or safety documentation when asked is raising flags.

Anonymity: a supplier that will not disclose legal name, address, or responsible person is not operating in a way that allows accountability.

I read post #57 twice before replying, because I had assumed the opposite.

Unresponsiveness: a supplier that does not reply to reasonable requests for documentation or clarification is showing you something about how they operate.

I disagree with the reply above, and I think the disagreement is substantive rather than terminological.

The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.