A computer-implemented method for creating text signatures for identifying spam messages may include: 1) identifying a spam message, 2) tokenizing the text of the spam message, 3) identifying at least one incorrectly punctuated token within the tokenized text of the spam message, 4) identifying, within the tokenized text of the spam message, at least one token that is adjacent to the incorrectly punctuated token, and then 5) creating a candidate signature for identifying future instances and/or variations of the spam message that includes both the incorrectly punctuated token and the token that is adjacent to the incorrectly punctuated token. Corresponding systems and configured computer-readable media are also disclosed.