Drug tests are horrible. Many places require them for employment, but it's a terrible violation of civil rights. Not only that, but it doesn't prove whether or not you're fit to do the job. The jobs that require drug tests don't give you a sobriety test when you walk into work, after all.
To that end, you shouldn't feel guilty about trying to cheat the system. The system is broken and oppressive, and so you should feel completely comfortable cheating on a drug test. That said, if you're going to cheat you need to do it right. It wouldn't benefit you to try cheating on a drug test, only to wind up failing anyway.
Many people talk about detoxification when trying to beat a drug test, and that is a possibility. However, it's a questionable possibility at best. You need at least a few days to detoxify properly, and how well it works depends on a number of factors such as size, weight, and overall health. Not only that, but if your urine winds up being too diluted to properly test, you'll only wind up having to test again. And that's if the company doesn't simply decide diluted urine is the same as failing.
Since detoxification works questionable at best, many people consider using synthetic urine. Synthetic urine is exactly what it sounds like. It's chemically designed to be exactly like urine, sometimes even utilizing non-human urine in the process. There are several brands out on the market, but not all synthetic urine is created equal.
The first thing you should keep in mind about synthetic urine is that you can not skimp on quality. There are many products that using a generic version is just as good as using a brand name version. Synthetic urine is not one of those products! Lower grade synthetic urine has a much higher chance of getting caught on the test. So do not try to go cheap!
Secondly, you'll need to be able to use the synthetic urine. Proving how weird and creepy drug tests are, many testing facilities have begun watching the person taking the test urinate, so that they can ensure there's no cheating going on. It will be difficult to use the synthetic urine in this case. In addition, if your company uses random drug tests, then you'll have to keep some synthetic urine with you at all times, just in case.
Lastly, remember that the temperature of the urine is important. Testing the temperature is one of the things the drug test does, after all. All synthetic urines need to be warmed up, and this often takes time. Some of them take up to 45 minutes to warm up properly! There's at least one brand on the market that includes a warming powder, but as you might expect it's quite expensive.
Ultimately, when looking at synthetic urine, there's one thing to keep in mind. You can not afford to buy cheap synthetic urine. If you plan on using it to beat a drug test, you need to make sure it's high quality.