They do this every time a President of the United States is leaving office. A bunch of college professors or other experts are asked who their favorite presidents were. And of course, we all get an amusing rank of the best American leaders from George Washington to whoever the outgoing president is. C-SPAN released a laughable survey of "experts" otherwise known as writers, historians and journalists regarding who America's best presidents were last week. People are entitled to their own opinions, but this survey has left more than just a few people scratching their heads about the validity of it.

Who was polled?

Let's take a look at who was polled before taking this too seriously. The reason this stood out so much for people was that our outgoing president was ranked so high. Rarely does an outgoing president manage to rank so highly in these surveys as Barack Obama did in this one, and rarely does a president with the facts of the Obama presidency rank so highly that often.

A record number of congressional seats lost in midterms, 47.9% average approval rating according to Gallup, first since the Great Depression to not see 3% GDP growth in any given year, and record national debt. As with a historical assessment of anything, how history is written depends on who you ask.

The C-SPAN survey is telling: the ideological tilt of the list of "experts" leans roughly 50% liberal, around 25% conservative, and only around 25% independent.

Do you want to know how out of touch such a tilt is? Lyndon Johnson, a president most of us don't think too highly of, managed to rank number 10 on this survey. Not good, folks.

How does one determine presidential greatness?

There are a number of factors to take into consideration when determining who America's greatest leaders were.

Obviously, if you ask one person about Franklin D. Roosevelt, some people will say he was elected four times because he saved the country from the Great Depression, enacted social welfare programs to help the American people, and saved the world during the Second World War.

Others may argue that Roosevelt prolonged the Depression with his social welfare programs, tried to pack the Supreme Court like a dictator, led the country into an unnecessary war, and violated the civil rights of Japanese-Americans.

As far as that stuff goes, it's all a matter of perspective.

Concerning Barack Obama, things aren't any different. The C-SPAN poll ranked him highly in the fields of "equality and justice for all," and "moral authority." Well, after Obama's support for the Obergefell v. Hodges Supreme Court ruling that has led to several instances of religious persecution across the country, there may be more than just a few Christians in the United States who would strongly disagree with both of those.

Approval rating is an important thing. Considering how President Trump's approval rating is starting out, he might want to take his legacy into consideration.

Obama ended his presidency with high approval ratings.

Yes, President Obama did happen to end his presidency with one of the higher approval ratings since Franklin Roosevelt. He also went through his presidency with one of the lower average approval ratings of any president since that same time. His average looks very similar to President Ford's average, and while Ford ended with majority approval he didn't have majority approval throughout.

That could be telling of how Obama will be remembered. Considering how revered this president is by the left and not so beloved by most others, it's very likely that liberals will continue to sing his praises for the next 50 years but he won't be looked upon too highly by most Americans in the future.

After all, who is it that honestly that still believes Lyndon Johnson was one of America's best leaders?