You cant be sure , everything is possible ...
Exactly so why put yourself into a situation where u even need to ask the question of possible manipulation? Thats why I stopped using them and all SB's a while ago, my stop was hit right on the nail then went in the direction I thought it would and cost me a few K.
I am not saying that CS manipulated the market for that 1-2 pips to hit my stop right on the nail, maybe maybe not, maybe that was the real market doing that to me and I did not make excuses to myself, but becasue I know they could and that doubt was in my mind it then made trading with SB's impossible and u may get to that stage at some point, plus speed and costs made me change also.
But anyway, enough of CS bashing, too easy a target and they do a very good job for the SB business model they are and demographic they are working towards, just keep them on their toes