If someone performs a job or task poorly or unsuccessfully, they will usually lay the blame on external factors, such as the quality of their equipment, rather than take responsibility for their own failure. After John spent all day assembling his new desk only to discover it was lopsided, he immediately declared that the package must have contained the wrong pieces. His wife replied, "only bad carpenters blame their tools, dear." The football player blamed the rainy weather for his poor performance, but as they say, a bad carpenter always blames his tools.