Mark Twain once said, “[…] When a merely honest man appears he is a comet–his fame is eternal–needs no genius, no talent–mere honesty-[…]”
Here’s a quick way to impress your clients. If they ask you a question, as far as you can, answer either “Yes” or “No” – whichever is applicable. And if you don’t know the answer, cop to it with “I don’t know but give me 24 hours and I can find out for you.” 24 hours is just a guide – choose however long you think it’ll take to find the answer; just make sure you stick to that deadline.
And if you still think honesty is for schmucks here’s another timeless insight from Mr Twain: “Honesty is the best policy – when there is money in it.”