Final answer:
In a spot test to distinguish between positive and negative controls, color changes or precipitate formation are typically being observed.
Step-by-step explanation:
In a spot test to distinguish between positive and negative controls, typically color changes or precipitate formation are being observed. A positive control is a sample that is expected to produce a certain response, such as a color change or the formation of a precipitate, whereas a negative control is a sample that is not expected to produce the same response. By comparing the results of the positive and negative controls, one can determine if the test is working correctly.