Is answering to old discussions good or bad for your earnings?

Certainly not. Answering to old discussion will never reduce your earnings. Mylot deletes those discussionw which violate Mylot rules and other discussion which are really not important. I have responded to discussion which were created four months back but my earnings never reduced.

If you are interested on that discussions I think you can response on it without worry your earnings will get reduced if mylot delete that discussions. but better if you response on new discussions so your response is up to date.

Mylot deletes discussions because they violate mylot guidelines, not because they have no responses. It is perfectly fine to answer discussions that are older. I would refer to the guidelines for further do's and don'ts. Remember mylot wants quality discussions and responses, not quantity. Good luck to you here at mylot!