Both 粗(cū)心(xīn) and 马(mǎ)虎(hu) means ‘careless’ in Mandarin Chinese and is commonly interchangeable.
However, 粗(cū)心(xīn) usually matches with 大(dà)意(yì) to emphasize the carelessness while 马(mǎ)虎(hu) would be changed into 马(mǎ)马(mǎ)虎(hū)虎(hū).
Tip1:
马(mǎ)马(mǎ)虎(hū)虎(hū) has already expressed the meaning of ‘very’, which can be understood as 很(hěn)马(mǎ)虎(hu), so it can’t match with evaluative degree marker such as 很(hěn), 非(fēi)常(cháng), 极(jí)了(le) etc. For example,
(1) 这(zhè)个(gè)人(rén)做(zuò)事(shì)很(hěn)马(mǎ)虎(hu)
This man does things carelessly.
(2) 这(zhè)个(gè)人(rén)做(zuò)事(shì)马(mǎ)马(mǎ)虎(hū)虎(hū)
This man does things carelessly.
Tip2:
马(mǎ)马(mǎ)虎(hū)虎(hū) can also express the meaning of ‘so-so’. For example,
(3) 我(wǒ)的(de)中(zhōng)文(wén)一(yì)般(bān)
My Chinese is just so-so
