I completely understand you! I'm trying to fight my urge to buy scratch-offs too. Ironically, I've walked away the last several times, but tonight, I broke down and bought 3. Granted, it was only $5 worth of tickets (which, of course, means really bad odds) but it was at a store I don't go to often but more people win scratchers there than any other place in town, so I thought I'd go for it.
This is how I'm actually walking away: before I buy PB or MM tickets, I look online at my state lottery website and see which scratch-offs are the newest. Then I check out the odds and how many winners have already happened. I decide at home how much I'm willing to spend and pick which ones I want. When I get to the place, if they don't have the scratch-offs I want, then I don't play at all. And because I usually only pick the brand-new ones, it's easy because they usually aren't out yet. However, I forgot to check tonight and bought ones that looked new. Ironically, the ones I bought were the old ones I hadn't seen before and the ones I thought were old, were the 3-day old ones.
Oh - and I only buy them from the vending machines. People are human and have figured out how to do teeny tiny scratches on some tix to see if they are winners, so I try to avoid those.
So tonight? I spent $5 on scratchers and won $2 - which is better odds than I usually have. ;-)