Some friend told me the word "deceitful" usually has a negative connotation.
Assume Alice's grammar is bad. Her teacher tells that her grammar is good to encourage her. Provided Alice's bad grammar is a fact, Her teacher tells a lie. Although the lie is to encourage Alice and hurts nobody.
Could I say the following?
The teacher is being deceitful to encourage her students.
where "deceitful" is being used as a positive word.
which means lots of adjectives that have negative connotations could be used as positive words.
Could someone please give a hint about the rules/conventions of it? Thanks in advance.