Actually it's not always correct and depends what you are looking for.why would be bad to gain bonuses? ahahah.. Of course it's good.
If you just care about playtime - then bonuses always good.
If you wish to increase your winning chances- more than half of casinos bonuses (actually more than 80%), will do just the opposite. You need to see if the bonus is cashable and what are the WR to see if it's good or bad.