ANSWER:

The prohibition is in spitting towards the qibla direction while praying.

It is prohibited to spit towards the direction of qibla and right side. Is the right side option applicable for every other direction also? There are many houses/offices that have their basins in bathrooms faced towards the direction of qibla. What to do in such cases?Cause people use such basins for ablution, brushing teeth, spitting etc.