Heywood, I understand that concern completely.
One way to avoid inadvertent screen touches is to set the ipad up on the keyboard dock on a stable surface, like a table or desk. The keyboard makes data entry faster and less error prone, as well.
I have not had any inadvertent touches using it that way, but I do sometimes accidentally hit the wrong spot when I am holding it in my hands, lying in bed, moving around, etc. It is rarely ever an issue that I would be concerned about, but if you were watching for the split second when to hit a button to make a trade, or bid on ebay, or such, you would need to be extra careful.
I have placed trades on Schwab with the ipad, but their website have a relatively foolproof system of needing to click multiple times through review screens before actually placing the trade or canceling an order. I have no concern about using it that way. But if you were using some other "one click" system it could be a problem.
I never use the "one click" feature on amazon for that reason, as well. (Except on the Kindle, where that is the only system, but that device's input via scroll and click is pretty slow and bullet proof.)