The three primary colors of
Red / Blue / Yellow have three diffrerent effects on the brain...
RED is the most reaction color to the brain - it actually hates it. Your visual sight notices red first before all other colors because once it is processed by the brain it actually tries to get to you 'look away' from the color red. Its 'initial shock' to the brain actually is why it is used in signs such as Stop Signs, or why a lot of stores use Red Sale Signs - your brain see these first, then after processing then actually tries to block them out (hence forcing you to concentrate again on the road or to look at the items that are on sale).
Yellow is neutral(actually if we include the base colors White is but we'll come back to that). In the color wheel yellow is taken as a color by the brain - processed - then will actually work with that color somewhat. Though not as reactive as red, it still gets attention. Making caution signs for example makes you see the signs from afar, but still keep focus on the surrounding area.
Blue causes the least reaction to the brain - its like the brains 'love color'. Your visual sight picks up the color and the brain can just continue processing it without almost no irratation - almost causing a calming sensation. Items which people want you to enjoy will make blue signs or vary on blue because it's carries a 'warm-soothing' effect on the brain (fact: Microsoft Windows for years has always come installed with a Blue / Blue-Green Background, or in recent years with Blue / Green Scenery because they want to to feel confortable in front of your monitor, almost confortable to stare at the screen... very sneaky on their pary don't you think?
Another fact: Wehn the 3D Fish Tank Screensaver first came out the reason so many liked it? Blue Water Backgrounds with just 'a touch of other color' in the fish to create a smoothing yet interested feeling... marketing has know these tricks about color for years...)
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Picking up from the three base colors - the secondary colors of
Orange (Red and Yellow), Purple (Blue and Red) and Green (Blue and Yellow) are used to create desired effects as well... to grab your attention faster and longer Orange is used, for vibrance, Green and for some excitement Purple.
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Now for th most evil color of all.... PINK! Pink is an VERY EVIL color... (and not because I'm a guy or a pink hater or anything) but because of what pink is made of and what it does to your brain.
Pink is the color white and red (now we talk about white). White is the main color in pink - and because it is the 'true' neutral color, your visual sight sees the color pink - but your brain only see the white FIRST. Because your bain has no issues with neutral colors it accepts the incoming and starts processing (or you continue looking at the pink)... but then *POW* that second color of red which has been there the entire time finally gets processed by the brain - but in almost all people too late before the visual intake has lated so long that now the brain must process the red as well - actually causing GREAT irratation (possibly headaches, mood swings).
Tests performed in prison holding cells have proven these effects - a violent person is put into a pink cell and left for a short time... within minutes the person becomes actually calm, almost 'spent of energy' - its the white. When left in longer - they actually became MORE volient than when they were first put in (after being calm for several minutes - they lose it!). The red has finally been processed but the long exposure hidden behind the white color now pushes them over the point. By the time you finish reading this information - you'll probably hate reading it (see - got ya 
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So now you know why Red can be annoying to look at - because even though I notice your posts immediately - to read any length of text is just too painful to look at
Here on POF - Extreme dark and light colors (black, white, yellow and grey) don't work well on both skins - so these go first. But as the policy states color should only be used to enhance a title or line of information and not an entire post.