They dropped leaflets on Caen hospital, just minutes before the bomb drop, but doctors placed an X in the courtyard and miraculously it survived as 30, 000 French people died from Allied bombs and turned Caen into a Monte Cassino-style sniper's dream.
Goodwood and Cobra are probably quite important in history, the allies had been developing ground/air operations since Italy, but St Lo/Falaise battles were probably the turning point in war. It was as simple as the weather. If the weather was bad, the German tanks were winning the war, if the weather was good, the German tanks were being blown sky-high by Typhoons and P-47s.
non-tactical bombing was atrocious throughout WW2, even at the end it took 30 lancs to hit a bridge or a ship and in 1941 only something like 5% of bombs were being dropped within 5 miles of the target.
Alot of famous operations killed more allies than Germans, e.g. Dambusters, Peenemunde, Caen etc. One notable exception being the raid on Amiens Prison, Operation Jericho which saved more prisoners than killed prisoners. The raid on the Gestapo HQ in Denmark didn't go so well though, they hit a school and killed scores of kids. Very hit and miss stuff, bombing, a lot of collateral damage.