Is it bad to cook frozen meat without thawing it?
It's really a question of taste. It's not going to hurt you, but there will be some undesirable effects. For example, to cook turkey properly, it must come to an internal temp. of 180. If the meat is frozen, it is going to take a lot longer for the internal temperature to rise that high, so the outside of the bird will be somewhat overcooked (compared to roasting a thawed bird). That meat will be much tougher than it would be otherwise.
If your question is querying as to whether it will cause ill health, then no, it will not. My mom does it all the time. Her roasts are tough, though. I have done this, but only when I am braising the meat, or using a slow cooker, which will cause the meat to be tender either way.
Just a note - it's 165 for turkeys - though you do may want 180 for the dark meat. Cooking turkey from frozen is explicitly allowed by the USDA: http://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/poultry-preparation/turkey-alternate-routes-to-the-table/ct_index/#8