Boycott P&G? Do you have any idea what you're suggesting? You might as well boycott eating.

Boycott eating processed shit, no problem.

Looking through the list of P&G brands, I can say that I haven't bought anything from them in years, even when I lived in the US.

I do agree though that boycotting every company that engages in questionable behavior would be near impossible. It's better to change the system, but if in the meantime you can avoid giving money to the most heinous companies then why not?

Is there a such thing as a partial boycott, where you just use less of something or avoid some of a company's products but not others? Perhaps there's another word for it. Either way, this seems like it would be useful too (maybe even more so because it's more realistic for people to do).

How could that possibly be effective?

Why wouldn't it? What do you believe the goal of a boycott to be?

The goal of any public pressure tactic is to force an organization to change its policy. Not to deny it revenue. If you're not doing the former, then all you're accomplishing with the latter is making yourself feel good about 'doing something'.

And how do you force it to change its policy simply by not buying its products? Why would a company, particularly a worldwide conglomerate, care whether you buy their products or not?

Hint: You've already said it.

Most chain grocery stores in the US have equivalent generics that are cheaper. This boycott is not only trivial but it saved you money.

Most "equivalent generics" are in fact made by the same companies that make the major name brands, in the same factories; they cost less because lower marketing expenses.

If you buy store generic-equivalents, its quite likely your money is going to exactly the same major corporation as the name brand in pretty much the same quantity (after deducting that the part that the major corporation would be paying to marketing/advertising firms to market the name brand.)

So, while it saves you money, it may not be as effective a boycott technique as you think. Unless your boycott target is the advertising industry.

Indeed. Here's the full list of P&G brands: http://en.wikipedia.org/wiki/List_of_Procter_&_Gamble_brands