Actually, the latest credit product systems from Experian and TransUnion (not sure about Equifax) allow creditors to see inquiry data as a list of dates. This array may include pre-approved offer checks and third-party pulls (such as those from Credit Karma). I believe you can even see this date list on Credit Karma as well.

In the same way that a debt validation letter is a "smell" to the debt collector that the debtor is concerned about their debt (and potential credit status), any indicator that the debtor is evaluating their own credit can also potentially raise the debtor's file with the collector to high-attention (or litigation) status (versus being sold off to another collector).