Who handles a counterparty's money is part of their pitch deck, whether they intend it to be or not. The choice of acquirer names the countries they can reach, the currencies they can accept, and the categories of business the processor above them has decided to serve. Read carefully, the payment layer often contradicts the marketing layer, and the contradictions are more honest than either party.
Neither is a verdict; plenty of legitimate businesses use higher-risk acquirers because their industry is mislabeled by default. Plenty of lower-risk businesses use them because their advisor put them there years ago and nobody moved. But the choice is data.
More revealing is the choice across multiple processors. A counterparty whose primary business runs on one acquirer and whose secondary business runs on another, where the second acquirer's profile does not match the second business's stated category, is a counterparty whose secondary business is being categorized in a way they did not advertise.
We also look at processor changes over time. A counterparty that switched acquirers three times in two years either has an operational reason, a pricing reason, or a risk reason. The third is the one worth investigating, and the public traces of the switch are usually enough to triangulate.
None of this requires looking at amounts or transactions. The processor relationships are surfaceable through receipts, terms of service, refund flows, payment-page metadata, and disclosures. It is a layer of research that almost nobody runs and that takes very little time once you know what to look at.