For example, I saw one that the hucksters say:
"Telescope is ideal for the young stargazer.
Great for star tracking, viewing wildlife, sporting events and more. Mirrored diagonal eyepiece. 24½"L. Durable, lightweight aluminum construction. Assembly required. Ages 13 and up."
It's terrible for star tracking. It can't track stars. It's got a cheap, awful photo-tripod style mount that makes it almost impossible to get any particular star (or planet, or even the Moon) in view, much less track it! Sporting events? Who's going to haul something like this, with its narrow field of view and stand and all to a game? Wildlife? Better hope it's sessile, because if it moves while you're trying to get it into view with this you're going to have to work at it twice as long.
If this scope is in your price range, get binoculars instead. There are many nice models of 7x35 binoculars and even some 7x50 binoculars available at the same price or lower than this terrible telescope. Binoculars really will be useful for sporting events and wildlife, and guess what? They'll be better for astronomy, too. You can get a nice pair of binoculars for about half the price of the above telescope, and spend the rest on a copy of Phil Harrington's excellent book, Touring the Universe Through Binoculars. It's a fine introduction to practical astronomy suitable for bright kids age 10-12 on up, or, for younger readers try H.A. Rey's The Stars, a New Way to See Them.
The reason stores put out items like the abominable scope above is simple. They sell. It's not like the people who stock the stores are really out to sell you something useless--they're probably just as unknowing as the people who make the mistake of buying them. Don't encourage them to keep stocking stuff like this. Pass it by.
And look at some of my previous posts for what to avoid in telescopes in higher price ranges. There are losers in every price bracket that you don't want to saddle someone else with. Don't kill a kid's incipient interest in science by getting them a bad instrument. Too often they'll blame themselves for not being able to use a useless device.
Microscopes as Gifts
While we're pointing out bad instruments for kids, let's talk microscopes.
If it has a plastic body, it's useless. Light gets through the plastic and ruins the image. If you're lucky, you'll see your eye. Chances are you'll see nothing.
If it has only high magnifications (100x and higher) it's useless. That's too high to use unless you have a really good instrument and an experienced user. I use a microscope for work, and I use 25x and 40x almost all of the time. A beginner's microscope has to have magnifications under 100x available. Optimally, the highest magnification on a triple turret scope for a beginner should be 100x or below (e.g. 25x/40x/75x or 40x/60x/100x. You get the idea.)
And it needs to have a metal body. So the light doesn't get in between the eyepiece and the object lens.
And they'll need a light, but it doesn't need to be one of the hot high intensity lamps so often sold for microscopes. The little mirror will be pretty much useless to a beginner. But a nice little white LED light (like a brighter model of book light) will work well for under the stage of the microscope (and it won't cook the specimens) and a handy table lamp without a shade or a desk lamp will illuminate opaque objects from the top.
And it doesn't need to cost a fortune.