Some things might be very offensive. I can think of many instances where non-multicultural translators translated complete ad campaigns for major companies without knowing that the word or words they had chosen were fine in the country where they were born but were very offensive in other countries. Well, bicho is a slang word for penis in Mexico. Kill your penis. Most of the time direct translations do not work.
Sentence structure is different in English and in Spanish.
A literal translation would be awkward and just that, a literal translation that has failed to be an instrument of communication or of expression. If you have to stop and think about what it's saying, or detect errors, you lost the attention and the respect of that reader. You get the idea from the English text and rewrite it in Spanish. Proofreading is as critical as writing. A wonderful, impeccable piece of writing can be destroyed by poor proofreading before the card is printed.