Trading in a rooted phone

[timbosslice]

I'm thinking of trading in my Samsung Galaxy S2 to CEX (UK). I have rooted my phone and I am aware that you need to use a USB jig in order to hide any evidence that you have ever rooted it, and to ensure the warranty isn't void. I have a stock gingerbread rom that I can flash prior to trade, so it will look like everything is normal. What I'm asking is, if I trade in my phone to CEX, will they test the phone to see if it has ever been rooted?

If they do then it is likely that they may not accept my phone to trade in..

 

[chillibean]

I wouldn't worry. surely they won't check to that extent and even if they do the worst they will do is decline to trade it in