It’s always a good idea to wash your pecans and other types of nuts before you use them, simply because they could still have certain chemicals or bacteria on them which you will want to avoid ingesting.
Whether you are eating your pecans out of the bag or using them in a recipe of some sort, it will be very important to make sure that you take the time to wash them thoroughly so you will be able to avoid ingesting anything potentially harmful.
It is also recommended that you wash any fruits or vegetables that you bring home from the store because they too could have harmful chemicals or bacterial agents on them.