Added a clause here: http://forums.backpack.tf/index.php?/topic/6033-guide-for-unusual-price-suggestions/. This wasn't really an issue until the site started allowing specific buy orders for unusual-effect combos. But this should be treated similarly to drops based on b/os and should be avoided in general.

"​Raising using quickbuyers

​Buyer trades alone can be used to raise the value of a hat only if these two criteria are met:

​-You are raising the value by at least 15%

-The trade must be up for at least 1 week"