This kind of dividend yield is very rare in the market.When evaluating dividend yields, I generally consider a sustainable 3% yield to be very solid. When I recently saw Dynex Capital's (DX +0.57%) massive 14.6% trailing 12-month dividend yield, I was skeptical, to put it mildly.However, the company has been making consistent monthly dividend payments dating all the way back to 2008, although the dividend has fluctuated a bit. Still, with a yield as high as this, a little fluctuation is OK as long as the co ...