how to reproduce color from a printed sample

I am surprised they are not sending you the color information.  I mean that would be the smart thing for your clients to do.  If they do not send you the color info then it will only cause problems.

Maybe ask to see their brand bible or style guide.  Or ask for the original files.

Take a look at Pantone Capture.

Pantone CAPSURE Color Measurement Tools

When using it you'll need good lighting.

Pantone 5 Light Booth | Color Evaluation

I agree that this is rather unrealistic, and reminiscent of what dear old Aunt Mollie would probably call "straining at a gnat to swallow an elephant."

If it's a proper logo, (i.e., one expected to be color-critical as all real logos should be), the color should be part of the logo specs, and should simply be obtained from the client or its design firm, not something to be interpreted from an instance of final print, whether by automation or otherwise.

However ostensibly "sophisticated" the scanner, it would still be interpreting, for example, an array of translucent halftone dots of CMYK process inks on some particular paper printed under some day- and ink- and press- and weather- and mood-specific press somewhere with who-knows-what level of hairsplitting colorimetric "accuracy." Pressmen can, and commonly do, make inkwell adjustments in the middle of a press run.

It's analogous to the pre-computer color house dictate to always strive to "match the original" before designers came to understood that mere algorithmic color calibration and real-world color correction are two different things.

JET

Not sure even a "hand-held" photospectrometer is your answer.  If I understand you correctly, you have printed samples which you have to match.  But, prinited how?  Are you looking at a magazine ad?  A brochure?  Can you get the original artwork for the given logo from the manufacturer or similar?  I think Pantone may have something as far as hand-held color meters go.  Check them out online.