If someone doesnt have good tajweed its not a problem, if someone is actually mispronouncing the letters then they have changed the meaning of the qur'an and it is impermissable to pray behind them and it shocks me that brothers are ok to tell you to pray behind one who changes the meaning of teh qur'an yet they say you cant pray behind a salafi because he wipes over his socks. SubhanAllah, this forum is a great reminder to me of why I should never follow sufism