Importing every public name from a module using a wildcard (from mymodule import *) is a bad idea because:
  -  It could lead to conflicts between names defined locally and the ones imported. 
-  It reduces code readability as developers will have a hard time knowing where names come from. 
-  It clutters the local namespace, which makes debugging more difficult. 
Remember that imported names can change when you update your dependencies. A wildcard import that works today might be broken tomorrow.
Exceptions
No issue will be raised in __init__.py files. Wildcard imports are a common way of populating these modules.
No issue will be raised in modules doing only imports. Local modules are sometimes created as a proxy for third-party modules.
# file: mylibrary/pyplot.py
try:
    from guiqwt.pyplot import *  # Ok
except Exception:
    from matplotlib.pyplot import *  # Ok
Just keep in mind that wildcard imports might still create issues in these cases. It’s always better to import only what you need.