After recent browsing of the interweb I've noticed a growing, and particularly worrying trend. To substantiate entirely un-scientific claims, people often mangle the word 'Science' in various stupid ways in an attempt to provide validity to whatever particular belief it is they hold.
In an earlier post I discussed the mechanic by which science works - being that of constructing a self consistent system.
This is where the proof comes into play. If you want to make grand claims about reality, there is an onus on you to provide evidence, and by evidence I mean rigorous, unbiased testing that can repeatedly show the claimed result in the real world.
So bias, the next issue. Whenever someone performs an experiment, it is to determine the result of putting a certain set of mechanics into play. It is highly unlikely that any person goes into an experiment without a thought as to what they think the result should be - this is unavoidable. The most important part is to examine the result closely, if a single piece of evidence does not hold true to the predictions made by your theory, whatever that theory may be - you must accept that your model is either incomplete, or incorrect - the extent of which is obviously determined by the scope of the error. This is good science, and it allows us to deal with something called 'reality'.
Bad science is where this is not done. When you pick only results that support your theory, then ignore or do not give import to the bits that don't, you have already managed to forfeit any credibility the study in question may have had. The universe does not conform to whim, deal with it.
Apart from the aforementioned badly performed science we also have those who are content to simply lie about the facts. Stringing together lines of meaningless waffle that at first glance may sound plausible, but work entirely on making statements that we know are wrong, and can easily prove to be so. A prime example of this is Answers in Genesis (Try not to growl while browsing that site, I find it particularly difficult).
Then we have people with pseudoscientific belief systems, Astrology for instance. You'll regularly see people talking about the 'science' of astrology, this is a particularly irritating example of what I've been talking about. Astrology is not a science, studies have time and again shown that under proper testing conditions it has about as much to say about the real world as a roll of the dice. Homeopathy? Its not even worth a full sentence.
In conclusion I'll add that covering your eyes and ears and shouting "lalala!" when confronted with contradicting evidence, or a sound reasoned argument does nothing for your credibility. Many out there seem to have a talent for ignoring or dismissing out of hand anything that does not have good things to say about their beliefs - if you want a defense that people will actually listen to, come up with an explanation that stands up under proper analysis.