Well, you should try to ask somebody to translate a random sentence (doesn't really matter what sentence) to a specific language. Then, you need to ask someone else to translate it back to the original language. I'm pretty sure that often the sentence will have remained it's original meaning, though it's likely to be a bit different. Though in some cases, depending on the language, and on the words you've used, a sentence could also change completely when translating it like that (there are a lot of google translate jokes who use that principle), though I'm pretty sure it's often not that different from the original. It's often bad luck when those things happen like the coca - cola billboard, I'm sure most of the time the original meaning is preserved.