I agree 100%, for that sometimes its better to avoid some bonuses time to time.
If you not are 100% and its not a really good one i recomend to you to avoid.
What are you trying to say in your post? What he is referring to is that you should take a look at terms and conditions and if it suits you then only accept them and sign up for casinos.The deposit bonus is different thing which you get when you sign up on casino but if you get other bonuses as well so why you should not take them? If you are saying anything else I am not aware of that but for casino should be legit and good response from them even if they don't give too many bonus to players.
I don't think we should get to a casino just because they are having good deposit bonuses or sign-up bonuses. Yes, we should look after them but that should not be the choosing criteria for any casino. I don't really get how it could be anyways. This is a one-time process, it could get you some bonus and kick start on any casino but that could not last forever.
Moreover, there are many bonuses, or most of the bonuses which require high wagering and it could be double the bonus amount or 25x or something like that. Also, the legitimacy of casinos can not be explained by the bonuses but by the way they operate.