Well yes, under strict rules, touching any ball, at any time, with anything other than the tip of your cue when shooting, is a foul. BIH being the exception, but you must place it with you hand and not your cue.
Not long ago ESPN was showing a 7-ball tournament I believe where they gave the players baggy sweaters with long sleeves and the announcers made several comments about players having to be careful not to let the sweater touch the ball. They were playing all ball fouls.
Of course most matches are played under conventional rules called cue ball foul only where incidental contact is not a foul.
Jake