As a tutor who works with adults, I find that students have various, and sometimes hidden, motives for seeking to hire a tutor. Sometimes these motives seem to have little to do with learning English, for example, and instead are related to such outside factors as a job promotion, a negative job review, an outside income such as blogging, or even as a way to gather inside information about how the business of tutoring works, in order to promote a similar business themselves. It's sometimes impossible for me to determine, even when I ask a straight-forward question, why a potential student is seeking to hire a tutor at this particular time. This can be difficult for a tutor who tries to plan a particular curriculum, only to find the process cut off just as it begins; it can also be difficult for a student who doesn't explain the real reasons and goals for the tutoring he/she seeks.
Let me give an example. A woman with advanced English skills came to me who had recently received an unfavorable job review during her probation period for a new position. I gave an assessment, developed a learning plan, and recommended textbooks. However, I only met her three times, when she suddenly told me she couldn't afford to pay for tutoring and hoped that if she kept her job after the next review, she could convince her new boss to pay for her lessons. Apparently she merely wanted to impress her boss that she had made an effort to learn, although in fact her three sessions were a waste of her time and money as she barely had time to begin any real study.
Tutors can hardly plan for and anticipate such "hidden motives" in an adult student. Despite careful questioning, I doubt there is a way to completely prevent such problems. On the other hand, I would strongly encourage adult learners to be open with a potential tutor, and tell them if you have limited time and resources, or if you have specific motives to seek tutoring, especially over a very short time span. If you are honest, a tutor may be better able to tailor work to meet your needs even over a few sessions, rather than think you want tutoring for some extended hours when you don't. Otherwise, your gesture may end up being a true waste of your time and money, something no one wants to see.