“What is the bad taste after tooth extraction?”

There could be a number of reasons you have a bad taste after an extraction: One could be that the tooth was infected and the bacteria or infection is causing an odor and bad taste in the mouth. It could be that food is lodged in the extraction site and causing an odor or bad taste. After four days, you should be able to comfortably brush your teeth now and decrease any bad taste you may have. It should also be okay to rinse your mouth out with a good mouth rinse like listerine, Peridex or a 1:1 solution mix of mouthwash and peroxide.
I hope this helps.

Dr. Z

Probably not normal. Have your dentist evaluate you. You may have a slight infection.