If you're on ANY hosted email platform and use stupid passwords, you will get hacked. This isn't exclusive to Gmail.
No business should be on any of these platforms.
joe12345@gmail.com just gives the business away as being a totally amateurish outfit.
I agree re google hosted email. I would not use it for other reasons.
Lots of companies in the US use google for their email. When I try to answer them through our server, google often put my letters into a spam folder. When I suspect that this has happened, I use a gmail account. And voila - the same text pasted to gmail always reaches the destination. Always. So, there are lots of reasons to use gmail.
I also noticed, when people first contact you, they sometimes use weird gmail account. This is because they don't know you and afraid you may spam them later. Then, once the communication is established, they switch to normal email.
Therefore, weird gmail address is not an indication of anything.
Anyway. Your approach to Chinese companies is totally unfounded. As everywhere, there are good ones and bad ones. I'm sure there are good and bad companies in UK as well.