Low price, large zoom range, good image quality - pick any two.
Or in other words, a superzoom doesn't necessarily have poor image quality, but then you really have to pay for it. I have a Sigma 50-500 which has pretty good image quality, but then it cost around €1400.
As you can guess from the Wikipedia article, there isn't any clear cut rule for when a zoom lens is considered a "superzoom". It isn't really anything that you find a zoom labeled with either, except perhaps for some cheaper models where the large zoom range is actually the only selling point.
So, don't look at the zoom range only. You won't get a lens that has enough range that you never have use for more anyay, but you can get a lens that easily covers all your needs almost all of the time.
When you are looking to buy a lens, user reviews can be of help. They will give you a rough idea of what image quality you can expect, but more importantly you will find if a lens has any flaw that you would be concerned with.