How do solutes affect the properties of solvents?
In many, many ways. Some you are already aware of, you likely just haven't made the connection.
Solutes can affect the taste, smell and appearance of the solvent. They can also affect physical properties like boiling or melting point, electrical resistance, and so on.
Solutes affect the solvent's organoleptic properties, such as taste, smell, appearance. As you've probably seen before, a vitamin C tablet, has a different taste from water with salt that has a different taste from water with sugar; anilin mixed with water has a different color than normal water, vinegar and alcohol have their own distinct smells and so on.
They can also affect the physical properties, you can check this out if you want, water with salt won't freeze if put in a freezer while normal water will. It will also take longer to boil than normal water (be careful if you're gonna check this last part).
More eletrolytes, that is species that make ions when dissolved means it's easier to conduct an electrical current so the more stuff in the water, the better it conducts.
Other stuff like viscosity, light refraction, how much light it can absorb at a specific wavelength, etc. can also be changed due to solutes and are often used as a parameters for analysis of certain products.
And of course, different solutes will provide different chemical properties to the solvent. So something like vinegar will lower the pH and so on.