I find them useful for terminology and very common phrases, but they're useless for anything else.
Most times the results are wrong, ambiguous, possibly offensive and almost always ridiculous.
For me, it is useful especially for translating Spanish words.
Automated translations are a good tool for what it does. It doesn't do everything.
Compare it to a hammer, it's good to drive a nail into wood. It's not good to crack an egg, even though it can do it. You need to learn how to use it, and need to leanr when not to use it.
BTW, even google gives you crap, don't moan, correct it with your feedback.
Maybe people look for easy things, easy life...if they feel they don't have enough time they will use theses services...
When I first saw Linguee I was impressed, but I'm becoming ever more sceptical about it. It uses a pool of multilingual sentences which are all correct in themselves, but the so-called 'translations' are machine-generated. For example, on an English-French translation page I came across an example of a phrasal verb used in an English advertising slogan for a cosmetic product. The supposed translation was simply the corresponding advertising slogan for that same product for the French-speaking market - needless to say the actual language of the two slogans was totally unconnected.
Use with caution.
I only ever use them for translating to a language I speak very well. It helps understand a text in a language I don't understand well/at all, and because I speak the language it translates into it's easy to see when the translation makes sense and when it produces nonsense, and sometimes you can still guess what went wrong in the translation. I also use them sometimes if I need to translate texts between two languages I know very well: the translator gives a rough translation and gives me a lot of the words translated and written down, then I improve and rewrite the text until it's good.