Well, I can't speak for Chinese hearing foreigners speak Chinese, but I can speak for myself as a Chinese speaking foreigner, when listening to other Chinese speaking foreigners. Some foreigners speaking Chinese, 我一点也听不懂, but with others its very clear and actually easier to understand than when Chinese speak it. It depends on their level. If their pronunciation is really bad and they are very new to Chinese, I can't understand. But more competent in Chinese, they tend to use the same word order and structure as other Westerners, which makes it easier for me to understand. When Chinese who don't speak 标准的英语 speak in English, it can be really difficult to understand and even grating to listen to. If a Chinese person speaks really good English and with a British accent, it makes them seem very posh and educated and sophisticated. But if they can barely speak English at all, work on getting the pronunciation, grammar, etc working and 标准 first.

people speaking chinese with an american accent is pretty entertaining, but chinese tones are hard, so if anyone tries, you have to give him/her some brownie points. i love hearing my chinese friends speaking english. their accents seem more british and different. actually, accents in general are cool! so, people, don't try to erase your accents because they become a part of your identity and personality.