Misused idioms on amateur blogs are not cause for surprise. When they appear in the writing of people who practice a profession, however, they probably warrant comment.
Here are two expressions that people who use them in a professional context ought to know the meaning of.
due diligence
In law, “due diligence” refers to proper attention to an undertaking in order to avoid committing an offense.
In US business terminology, “due diligence” is the “comprehensive appraisal of a business undertaken by or on behalf of a prospective buyer, especially in order to establish the exact scope of current assets and liabilities, and to evaluate future commercial potential.”
The adjective due in this phrase means appropriate.
The noun diligence means “earnest and persistent effort to accomplish what is undertaken.”
A person practices or performs “due diligence.” One may even “do due diligence.” One may not, however, “do do diligence,” as this plastic surgeon advises a questioner on his site:
You should do do diligence by checking the website of the American Board of Plastic Surgery, ASPS® and ASAPS® to evaluate the physicians [sic] training.
Nor can one “do diligence,” as this business consultant advises:
Do your diligence and make really sure before accepting an offer of employment here; ask the right questions.
to eavesdrop
The noun eaves refers to the edge of the roof that overhangs the side of a building. People often stand under the eaves to shelter from the rain (under the drop of the eaves). When they do so, they may be close to a window. If the window is open, they may be able to overhear a conversation that’s going on in the adjacent room.
Literally, “to eavesdrop” is “to stand within the ‘eavesdrop’ of a house in order to listen to secrets.” Figuratively, “to eavesdrop” is to listen secretly to private conversation. Eavesdropping is the noun for the activity. An eavesdropper is a person who listens secretly to the conversation of others. Nowadays, it’s possible to eavesdrop electronically.
I have seen the following maimed versions of eavesdrop and its forms:
The US is weighing its ease-dropping on western leaders’ policy—Newspaper headline (The incorrect spelling is also used three times in the article that follows).
Feinstein Accuses CIA Of Ease-Dropping On Senate Panel Computers—Google article summary.
I went into her room with my head down, she said you were ease dropping on the phone, weren’t you?—Published novel.
The words are closed compounds: eavesdrop, eavesdropping, and eavesdropper.
When I enter ‘easedrop’ or ‘easedropping’ into dictionary.reference.com, it comes back with “Did you mean eavesdrop?” So, due diligence in editing would lead to the authors correcting their writing. Of course, neither ‘do diligence’ nor ‘dew diligence’ would suffice.
“…neither ‘do diligence’ nor ‘dew diligence’ would suffice.”
Neither does ‘dude diligence.’ The attempt has been made.