Read a good book on sales, like one by Zig Ziglar. Effective sales is not at all about lying to customers. The best sales professionals rely on repeat sales, and you don't get repeat sales by lying to your customers.
I have a technical degree, and it includes zero sales training. Even born salesmen need practice and training.
BTW, when Boeing sells airplanes it sends out its top engineers. Engineers with sales training make darn good salesmen for highly technical products, and there's no way in hail you're going to sell an airplane to an airline by lying to them.
Also, if your product really does suck, get a job working for someone who has a better product. If no one has a better product, build it or do the best you can with what you've got. There's quite a bit of that in software where the best product simply doesn't exist yet, so sell the current best despite its shortcomings. Great salespeople have to be sold on the product they're selling before they're willing to sell it to someone else--it's easier for everyone that way.
Sales is all about understanding people quickly and helping them get to where they want to go, I'm not sure why technical people often have a problem with this but I suspect it has to do with an underlying lack of confidence when it comes to people and asking for things; it's not that they're inherently more honest than people who work in sales, I've heard that one plenty and I find "honesty" (as they see it) is usually just an excuse for their timidity, something to hide behind. And your average salesperson probably is a hack, but so is your average engineer.
IMHO, this is a big reason why technical people struggle in sales: they're likely to be more honest/open about the limitations of the product when asked.
The less the saleschap knows about the product/service in question, the more he can confidently claim. Also, it helps when the sales function is separated out from delivery and support, as they can ensure that the next pitch is not coloured by those sausage factories.