I'd say that ESTps are blunt rather than honest -- if you define being "honest" as a principled stance based on ethical understanding.

I don't think that ESTps tend to think - or feel - that they have to be honest because lying or being dishonest is intrinsically wrong.

Rather, they are blunt, in the sense of speaking their minds with little regard for other people's feelings, because of their big egos (which leads them to think that others will love to hear their views no matter what) and little ability to foresee how they might hurt or annoy others.

But that doesn't mean that an ESTp is less likely than other types to lie, especially if it's about saving their all-important skin or getting what they want.