Yeah, they may look fine for people who don't know language other than their own, otherwise you will just notice that they just translate badly and sometimes even mistranslating (or not translating at all) key words. This is especially true for anything that is not a simple conversation between people, or other simple sentences.

It is also not helpful due how they work - while translating from English or to English may be working occasionally well, using any other language combination such as Polish -> Russian works terrible even though they are more similar to each other than let's say Polish -> English. "Why?" you may ask. It's all because it is always translating first to English and then to target language, and that's a guarantee to shitty translation, but somebody with no knowledge of either basic linguistics or at least intermediate level of foreign language may not be able to comprehend why is that a hard/impossible task.

To put it simply - For any more complicated text you are always sacrificing some context in translation, or make it more ambiguous. If you do it twice you are just making shit up.