Spiritually speaking, is it a good answering strategy to judge the motives of a questioner?

I am often attacked for my supposed motives in asking questions about such topics as Darwinism, homosexuality, and Islam. Is it a good answer to say I must have bad motives to ask about these topics? If so, how can one know an asker's motives, and doesn't it limit inquiry to rule some topics off limits for inquiry? If not, what benefits do motive-judging respondents gain?