Are you doing Scrum, or are you doing Scrum-But?
Many teams use the Nokia Test to evaluate their Scrumness. Bas Vodde presented the original Nokia Test in 2006; he used it as a simple way to evaluate the Agileness of development teams at Nokia. In 2007, Jeff Sutherland adapted the Nokia Test to Scrum.
Ken Schwaber recently developed a more comprehensive Scrum assessment. You can use it to evaluate your knowledge of Scrum and see how it improves over time. Ken is also using it to understand the Scrum community's knowledge of the Scrum Guide.