If you actually read the rules you'd know that what you're implying isn't true.

No sharking. Sharking is defined as manipulating another user into trading/selling a valuable item for 10% or less of its accepted value (or 20% or less for users with less than 200 hours in that game) or any other deceptive trading practice that the staff consider to be against the spirit of this rule. We participate in a network of trading sites that do not tolerate taking advantage of other users for personal gain.

Other than that it is a free market and no price guides are being endorsed, that doesn't mean sharks or trolls will be tolerated.

2 refined for team shine scattergun killstreak kit ($7) is totally not a scam.
Reporting users who have trades like that just gets responded with
"We do not tell our users what they have to buy or sell their items for. If this person's prices aren't what you are willing to pay or sell your items for, try using our SEARCH feature while will help you find a better price. Thank you for the report though."
-- But that's not what this thread is about. So let's leave it at that and get on to the question, eh?

The amount of users misusing the report function is insane. People think that someone buying a craft hat worth 1.33 Ref for 1 Ref is scamming. To my knowledge Killstreak Kits aren't part of pricing guides so checking the validity of each individual report is very time consuming and moderators have better things to do than check if a specific Kit does sell for well above 2 Ref or not.

To prevent your reports from being overlooked and to make moderator's lives easier, provide proof with completed trades and/or market links that prove that it does indeed sell for $7 otherwise one might assume that you're just one of the many traders who misuse the reporting system.

So nobody has any tools to hide trades?