it is not polite to use 谢 to someone.so if you really want to express your thankness,use 谢谢 or 谢谢你.谢了 is also not very polite but much better than 谢.in our culture,abbreviated words are usually used in the case when superior talk to subordinate or senior talk to junior,like father talk to son.if you want to show your respect to someone use more characters instead single,like if you want to say ok,use 好的 instead of 好.
and never use 谢他,it is the transcription of shit in china.who told you use that must be joking you or he dont know chinese.
thx
or3x
on the internet. (Chinese3
sounds liketh
). And single char谢
may also means谢绝
or谢罪
, which has totally different meaning.