Answer these questions honestly and find something out about yourself. More to the point, can you do anything about it?
1) Do you show movies to your class? If so what is your motivation for doing so? Is it to complement the material presented in class? Is it an occasional reward for your students for achievement or good behavior? Or is it so you can burn valuable time because it is easier for you to show a movie than actually teach something? If you show movies to your class and at the end of the "lesson" they have learned basically nothing.
2) Do you miss class often or for any excuse? If for example you must make an off campus appointment on a school day, do you schedule your appointment around your classes or do you use the appointment as an excuse to miss class? If you answer is yes to these questions chances are you really don't care too much about your your students.
3) Do you often play games in class that really have no/little value in terms of learning? Like showing the movie that burns time because you are too lazy to teach, playing games can be valuable or they can be an indication that you may be a crappy teacher.
4) Are you a "smart guy" that has "figured out" the system? Is your primary goal to keep your job while doing as little work as possible? Do you give away candy and treats to your students so they will like you? If a kid is struggling in class do you just give him more homework because you know that Thai parents equate lots of homework with good teaching?
5) Do you like to boast how good it feels to see your students learning when in fact you you know they are not learning much if anything at all from you? You figure by saying these things others you will deceive others into believing that you actually care if your students learn or not. Chances are you are not fooling anybody.
6) Do you yourself spend a lot of time playing video games shooting up bad guys in an apocalyptic future world or watching inane TV shows? Well everybody needs to relax and put the brain on hold but the amount of time you spend on non-creative activities such as these is related to how creatively your mind works in general and is also an indicator of your capacity for sloth. Lazy, non creative people generally aren't very good teachers. Chances are if you spend a significant amount of time watching TV and playing video games, you may be a crappy teacher.
7) Do you spend most of your time sitting or standing in class? (This is more directed to teachers working with kids rather than in corporate or language school situations). An enthusiastic teacher will be on his or her feet for the vast majority of time. If you stand and move around the class your students will focus more on you, that should be evident. If you spend more time on you lazy rump than up on your feet.........you might be....you guessed it.
8) Do you give lots of classwork to fill time? Most of the people reading this are teaching EFL. As an English teacher in a foreign county chances are your school has hired you so that students have a chance to interact with a native speaker to practice/acquire speaking and listening skills. Some classwork which underscores speaking and listening activities is appropriate(and of course it depends on curriculum dictated by course). BUT if you throw classwork at your students so you can sit down and relax, that's just a cop-out
9) Do you have control of your class? Sadly, even if you are giving it your all, if you can't control your classes, you are probably not effective as a teacher. Even if you have the luxury of an assistant who keeps order for you, if you can't control the class yourself, chances are your students are not focusing on what you are teaching. They are just responding to being disciplined. You need to be able to control your class. You may be trying, but if you can't control your class you are probably a crappy teacher.
10) Honestly, do you really care if your students learn or not? Is your job just a way to make a living? I guess it is possible, but in my estimation if you really don't like teaching and if it doesn't bother you when a class doesn't go as well as it could, you should get out of the game.
So now what? If you have evaluated yourself honestly and you have come to a conclusion that you are in fact a crappy teacher what can you do about it? Since most of these things actually have to do with personal motivation, probably not a lot. Laziness and indifference are character flaws and nothing short of a miracle can do anything to change that. If that is your problem my suggestion to you is pray for improvement, but don't hold your breath. If however, you have problems with class management, or finding ways to be more effective in class, you can go to the powerteachers website and learn how to become a Whole Brain teacher. This will solve your problems as long as an aversion to WORK is not your fundamental issue.
Happy Teaching (or gold bricking, whichever the case may be!)