Russian term (edited): рыльце в пушку

unclean hands n. a legal doctrine which is a defense to a complaint, which states that a party who is asking for a judgment cannot have the help of the court if he/she has done anything unethical in relation to the subject of the lawsuit. Thus, if a defendant can show the plaintiff had "unclean hands," the plaintiff's complaint will be dismissed or the plaintiff will be denied judgment.
http://legal-dictionary.thefreedictionary.com/Unclean hands

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Note added at 1 hr (2006-03-09 23:49:32 GMT)
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While possessing a legal power, in common speech this expression means "be mixed up in the affair". And the fact of beeing a legal term secures its unifom understanding anywhere...

Основываясь на идиоме "to have one's finger in the pie": http://idioms.thefreedictionary.com/have a finger in the pie
К сожалению, оно само по себе недостаточно негативно звучит, поэтому я постарался придать дополнительную отрицательную окраску вот такой вот модификацией.

Кстати, еще же есть поговорка "sweep your own porch clean first", т.е. "в чужом глазу видим сучок, а в своём бревна не замечаем". Не подойдет?

Russian term (edited): у самого рыльце в пушку

Example:
Ted accused Bob of being unfaithful to his wife, but that's like the pot calling the kettle black.

То есть, они оба черные (чугунные).

This is what came to mind for me