NEW YORK (TheStreet) -- Warren Buffett has been anything but shy when it comes to expressing his optimistic view towards the U.S. economy. Whether it is through newspapers, television interviews, or face-to-face interactions like his annual shareholder's meeting, the billionaire investor has remained unwavering in his bullish projections for years.Adhering to the mantra that investors should, "be fearful when others are greedy, and be greedy when others are fearful," Buffett has continued to put his money were his mouth is, expanding the reach of his legendary investment empire, even as the market's outlook remains overcast. Given his rosy comments, some may feel that Buffett is the epitome of a perma-bull. The fact is, however, that the Oracle of Omaha is not blind to the most pressing challenges facing the economy today. Construction, for example, is one industry that he has continually held reservations towards.