No, they're not a waste of time. Yes, it depends on the site.
What I notice is that so many men talk about what they like to do, without ever mentioning who they are inside. Such as, "I'm usually an upbeat kind of guy, warm, big-hearted, affectionate..." They talk about their outside. The interesting thing is, guys who are emotionally available comb the ads looking for a profile that "speaks" to them. Talking ONLY about your hobbies doesn't always catch the right guys. If you want closeness and intimacy, then make your profile one that talks about that. I usually mention how much I loved my mother (and was loved back) and one or two things she taught me ("Give because you want to, not because you expect to get something in return." I've noticed the guys who respond to me mention that they liked reading that, that they also loved their mothers. So, my profile speaks to something they can relate to. Yours should, too.
If you just want companionship, feel free to say that, a little about who you are inside, and what you enjoy doing with your time. Just make sure your profile speaks to what you have inside of you, because once you meet the person, they'll see who you are, and if you left out certain things (your temperament is on the cold side, you have a temper (which I wouldn't imagine anyone seeing that on a first date. Well, for me, at least, that'd be a deal breaker), etc., there won't be a chance to entice them. I think the expression, "Make a good first impression" is true, but the impression should be one that's authentically YOU.
And whether you are a "catch" or not depends on who is looking at you. Some people see the things about you that make you someone they want to know. But if someone is superficial, they'll miss what makes you special, because they're only looking for the "surface" things (great body, good looks) that dazzle so many guys - until they get to know the person and realize that that person's "outside" is all they have to offer. For some, that'll be enough...for a while.
Just SHOW YOURSELF.