Remember that anecdotes, however compelling, don't really prove anything. There have been (and always will be) wondrous tales of miracle cures and miraculous remedies, extraordinary opportunities and exceptional successes. Some of these tales may be true, and some could be true. But stories about others' amazing experiences in, say, purchasing a product or making an investment are rarely worthy of unmitigated trust. Anyone who invested with Bernie Madoff, for example, found out only too late that their wonderful returns had been bogus all along. So be suspicious of anyone's trying to convince you to do something on the basis of tales and anecdotes (particularly undocumented ones). Listen with interest, if you will, but be careful not to suspend your skepticism.
Don't assume that another is "savvy" on a matter merely because you yourself are relatively ignorant about it. Either bring yourself "up to speed" on what you should know more about if you're to make an informed decision--or, at the least, consult a friend or professional whom you feel confident has both substantial knowledge in the area and can be disinterested enough (i.e., has no emotional or financial stake in your decision) to fully share their superior knowledge with you.
Further, don't worry about sounding rude. Generally speaking, you're little more than an object to them anyway. And salespeople (or people who make "cold cools" generally) typically have pretty thick skins, or they don't last long in such a manipulative role. (Personally, what I find most amusing about phone solicitors is that it's so easy to tell when they're reading from a script, yet making an effort to sound heartfelt and sincere, which regularly prompts me either to roll my eyes, or shrug my shoulders--or both).
That said, it's all too possible that if some substance has put you in a disinhibited frame of mind, your internal censoring mechanism may be so dulled that you're unable to keep your prior word to yourself. If you already have a record of betraying yourself while in an altered ego state, you need to consider whether you can afford to give yourself license to "use" in any situation where you may not be able to resist an appeal which, stone sober, you'd almost automatically refuse.
As Baumeister (2001) himself puts it (though not specifically linking his thesis to increased gullibility): "The exhaustion theory holds that once the self has become depleted, it lacks the resources necessary for further exertion of volition." In short, fatigue leads to an attenuation of will power and self-restraint. So we're much more vulnerable to being gulled when we make decisions when we're tired. We're simply not in the right state of mind to make choices, take responsibility, or exert self-control when the finite energy resource to do so wisely has temporarily become exhausted.
Consequently, you should be especially careful not to commit to anything when your emotions are highly charged. Whether you're in love (or, for that matter, "in hate"); or maybe boiling over with anger, sinking from the weight of depression, or trembling with anxiety, strong emotions just aren't compatible with optimal neocortical functioning. In such a state, your newer, more evolved brain has been sabotaged by your older, reptilian (or dinosaur) brain. And any behavior undertaken in such an emotionally pronounced state is likely to lead to later regret.
The emotion of enthusiasm, too, can be dangerous if it's based less on reason than credulousness in the face of some smooth talker--someone especially adept at inspiring confidence without providing corroborating facts. As Greenspan (in his Annals) succinctly observes: "When emotion walks in the door, reason flies out the window." Perhaps this much skepticism about emotion is a bit overstated, but it's still wise to be wary and step back when rising emotions begin to dominate your thought process.
Note: Here are links to Parts 1 ("How Vulnerable Are You to Being Duped"), 2 ("Childhood Origins of Gullibility"), and 3 ("More Negative Self-Beliefs That Can Lead to Gullibility") of this multi-part post. Part six will add a final seven suggestions to the seven above (and the seven offered initially in part four).