An emphatic expression meaning 'each and every' or 'all of them', often used to complain or emphasize that everything without exception is in a certain state (e.g., 'They're all no good').
どれもこれも値段が高すぎて買えない。
Everything is too expensive; I can't buy any of it.
彼の言い訳はどれもこれも信じられない。
None of his excuses are believable.
どれもこれもやりたがって、結局何も終わらない。
He wants to do everything, and in the end nothing gets finished.