You buy or sell into a trade and if it immediately goes for you, its usually about 5-10 pips over a few minutes. If it goes against you, its always 20+ pips over a few minutes. Also, i dont know if its my platform or what, but whenever I am about to sell, as soon as I put my mouse over the sell button, the price almost instantly goes lower. If i put it over the buy button...it goes higher. This can be repeated 90% of the time if i wait a few seconds before each time i do it. I gotta wonder if its in the programming in an attempt to cheat you out of a few pips.
What broker are you using? I haven't seen it myself, but you can easily exploit it: if you want to sell hover your mouse over the BUY button for a while, and when the price moves up quickly hit SELL!