dubious

1 - Scientists are dubious about the applicability of the new method although they put a lot effort in devising it.

2 - Millions of dollars of peoples money are being given away for often dubious projects in the form of Federal Grants.

3 - Doctors were dubious about his chances of survival.

4 - Chemical lasers are widely discredited by scientists, who are dubious about the prospects for turning them into weapons.

5 - Polls show Americans are increasingly dubious about global warming, even as most climate scientists say they're ever more sure that it's real.