Many tea party critics accuse the movement of racist tendencies. Their evidence includes its obsession over illegal immigration and nasty epithets hurled during tea party rallies.

But those who would point fingers at all possible displays of bigotry would soon run out of digits. Trying to determine what is racist can be a very confusing exercise. The same policy can be deemed both racist and non-racist. And wholesome causes can attract unsavory bedfellows.

Many readers reproached me for implying racist motives in their support for the new Arizona immigration law. I had done no such thing. While some no doubt back it out of prejudice, the measure's purpose is to solve the vexing problem of crime and public cost tied to illegal border crossings.

I did term the law "misguided" for effectively singling out Latinos for special scrutiny. By empowering the police to demand papers of anyone suspected of being in the country illegally, the law could turn racist in practice, if not intent. That's a problem.

Tea partiers can rightly complain that they've been unfairly generalized as bigoted. During their Washington protests last March, a handful of attendees shouted disgusting things at black Rep. John Lewis (D-Ga.), and gay Rep. Barney Frank (D-Mass.) African-American Rep. James Clyburn (D-S.C.) was spat upon.

Who were these miscreants? We have no idea. Nonetheless, an entire weekend was devoted to tying this offensive behavior to the tea party movement. While some reporters opened the possibility that the bad apples were a minority among the tea party masses, none speculated that they may not have been members at all. They could have been exhibitionists attracted to the cameras or double agents trying to tar the phenomenon as racist. We'll never know.

Yes, rapid demographic changes alarm many Americans, who see immigration control as a way to restrict the inflow of "non-whites." Call them racially motivated, if you will. But turning a blind eye to open borders can also have racist effects: Mass immigration displaces unskilled American workers, very often blacks (and now many Latinos, as well), with cheaper foreign labor.

Janitors in Los Angeles used to be unionized and largely African-American. The influx of undocumented Latinos broke the union and destroyed jobs held by unskilled blacks. The Latinization of Miami has breathed new life into that city, but at the price of lost employment for the blacks who long labored in the hotels and restaurants.

If the newly jobless were white people rather than blacks - say, if teachers' unions were broken up rather than the janitors' - the case against uncontrolled immigration would have been more forcefully made in polite, progressive circles.

I'm for family planning. But it remains undeniable that the birth-control movement, started in the 1920s, was partly inspired by the desire to curb "undesirable" populations. As Margaret Sanger, founder of the American Birth Control League, worried, "Those least fit to carry on the race are increasing most rapidly."

One can distance oneself from such ugly sentiments while holding that Americans deserve the right to decide how many children they have. Planned Parenthood gets another check from me.

Sierra Club leaders condemned as racist members wanting the environmental group to endorse a stricter immigration policy. The dissidents argued that the club's call for population control was meaningless if it didn't address the main source of our expanding population: immigration. Their concerns centered on numbers of people, not their color, the dissidents kept saying - but to no avail.

What is racism, and who is racist? The answers are not always easy. You think you know racism when you see it, but everyone has a different set of eyes.

Froma Harrop is a columnist for The Providence Journal.