df = pd.DataFrame({'A': np.arange(500), 'B': np.arange(500.0)})
df.loc[321, 'A'] = 'Fred'
df.loc[325, 'B'] = True
weird = (df.applymap(type) != df.iloc[0].apply(type)).any(axis=1)
What's a good strategy to find mixed types in Pandas columns?