Wall Street's bond bears smile as they read their press clippings» count their profits and repeat their gloomy forecasts. They were right again in the first half of 1981. Interest rates on loans, bonds and mortgages continued to rise, with only brief pauses and short-lived reverses. True, the bears missed most of the often sizeable, monthly ups and downs of interest rates. But they got the direction right. And that's better than many of us did.