There are some warning signs that you might have a bad e-mail address. First, is it oddly specific, but does it end in a number? You probably need to rethink your life. Anything along the lines of NobodyLovesTheCircusMore5 or ClevelandMortThePirateHunter7 is just a cry for help. The people who own these e-mail addresses clearly felt that they had their lives well in order until they noticed that NobodyLovesTheCircusMore was taken -- four times. At Hotmail.
My old email address falls roughly within these parameters, being based of all things off the 90s puzzle game Myst. Mostly I picked it because it sounded neat, and an unrelated number was en vogue at the time.
I hold onto it now for a few reasons: many of my friends and family already have that as my contact and switching is just mildly inconvenient. It's also a good way to separate personal and business mail. Finally, I have a peculiar loyalty for it--fifteen years of providing email under the same goofy name is not casually tossed aside.
h/t Ezra Klein