Clean the dip stick well. I also cleaned the tube that it fits into.

After that, the dip stick looked clean for almost a year.

BTW - I cleaned the tube by tying a long, thin rag to the end of the stick, and wrapping it around the stick 3 or 4 times. It took three rags, but I got it clean.

The dip stick tube is in front of the engine, and does not warm up on short trips, but your region should not be too cold.
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'96 855R, '95 855, 854, '90 744 TI, 366,000 miles put on 7 bricks

I would not put any kind of cleaner or solvent or anything other than the proper quantity of the specified type and weight of oil in a car engine.

You might have some muck on the dipstick if the car is often driven on short trips so the engine does not heat up really thoroughly. It would be brown and/or milky. There wouldn't be very much. Worse in cold climates.

Look under the oil filler cap (feel around with your finger) to see if there are any foreign-looking deposits there. If not much is found, I would ignore what is found on the dipstick.

If there is brown or black varnish-like stuff, or a burnt smell - what's the history of the car as to mileage driven, type of use, and frequency of oil changes?

When you open the oil filler cap you can also see one or two of the cam lobes - do they look burned or very badly scuffed? If not that would suggest there may be nothing serious wrong.

I would drain the oil, put in 4 qts ATF and let it idle for 15 - 20 mins. Then drain replace the oil and filter. Then check it at about 500 - 1K miles.