have feet of clay → έχω κάτι στραβό, έχω κάποιο κουσούρι

[crystal]

have feet of clay → έχω κάτι στραβό, έχω κάποιο κουσούρι
 
to have a bad quality which you keep hidden
Some of the greatest geniuses in history had feet of clay.
http://dictionary.cambridge.org/dictionary/british/have-feet-of-clay#have-feet-of-clay__1