LOUD AND CLEAR means Excellent copy with no noise; while LOUD BUT DISTORTED never meant the signal strength is very strong but means that the audio is distorted.
A plain-language radio check is the means of requesting and giving a signal strength and readability report for radiotelephony (voice) communications, and is the direct equivalent to the QSA and QRK code used to give the same report in radiotelegraph (Morse code) communications. LOUD BUT DISTORTED means the signal strength is very strong but the audio is distorted. 
