In one of my Writing classes, I just gave a test, and one of the questions was "Identify the problem with this thesis statement" -- we'd spent a lot of time talking about Thesis Statements.
Some of the problems in the thesis statements were things like:
"not specific enough"
"support does not use grammatically parallel form"
"not controversial" (for example: "Exercise is good for you" is not a good thesis statement, because most people would read it and say, "DUH")
"does not take a clear position on the topic"
"uses absolute language, making the thesis difficult to prove"
The thesis statement was:
"There are three reasons all Americans love hamburgers: they are cheap, convenient, and tasty."
The correct answer was
"This thesis statement makes an absolute claim that cannot be proven" - that is, the word "all" makes the claim indefensible, and should be replaced with a word like "some" or "many" or even "most" -- leaving room for exceptions to the assertion.
About a third of my students thought the problem with the thesis statement was
"This statement is not controversial"
Turns out "All Americans love hamburgers" is a self-evident truth. They're Americans, after all.
And all you can do is smile.