You won't be for long if you do. After the third or fourth time you find yourself standing at the counter waiting for help while the clerk is literally standing two feet away from you in a personal conversation with a friend for five solid minutes without even acknowledging your existence, you'll be boycotting again.
A year or so ago I went in there and bought $800 worth of products. Then I went to two different counters in two different departments the next day while trying to buy a couple of things I'd forgotten the day before, and got the attitudes I just described. I literally tossed my intended purchases onto the floor in front of the second counter (nothing breakable, I just wanted to make them pick it up), went home, gathered up all $800 worth of merchandise (all of which had been opened and used, heh heh) and went right back to Sears, walked right into the managers' office, and put it all on her desk and made her pay me back every penny IN CASH, telling her if she didn't, I was leaving the items on her desk, going home and calling my credit card company to inform them all products had been returned as defective, and the I was calling the CEO's office that evening and naming every name. She had to clean out three different cash registers to get rid of me. And a cursory inspection of the jerk counters around the same time of day a week later showed no sign of the workers that had snubbed me.
God, that felt good. And if just goes to show that if you treat them like they treat you, you can really make them pay for their actions.