I never use the sites either, I can read and translate 95% of the document and certainly understand the subject, context and message, there may be a couple of words to look up. When I have used a translator it has given out rubbish that makes it much harder to understand the original, when people post Google translates on forums and ask "what does this mean" I have to ask for the original to be able to answer.
When composing something I dont need a translator and would not dare use one having seen the results, again there may be a couple of words or phrases that I may need to look up but when I compose something mentally I am doing so in French and using the vocabulary that I have.
I find Linguée.fr excellent and it will often give me a better word or phrase than I would use and lots of different contexts for a word or phrase.
Even at the very beginning I would not use web translations, they were frankly appalling back then.