When it comes to finding synonyms for the phrase "wast insincere with," there are a variety of words that can come to mind. Some possible options might include words like disingenuous, false, insincere, hypocritical, or even deceitful. Each of these words conveys a sense of dishonesty or lack of sincerity in some way, suggesting that the person in question is not being completely honest or forthright in their dealings with others. Whether used to describe a person's actions, words, or overall demeanor, these synonyms all convey a sense of negativity and suggest that trust may be hard to come by when dealing with someone who is not being genuine.