Just to clarify, Jose Canseco is an opportunistic lout and all-around lowlife. He squandered away the bulk of a Hall of Fame-potential career and now is selling out his former teammates in a desperate stab at a quick buck and another 30 minutes of fame.

But here's the scary part: As sleazy as Canseco is, and as distasteful as his motives may be, you simply can't dismiss his latest round of outrageous accusations out of hand. Not anymore.

Canseco injecting McGwire in the buttocks in the bathroom stall, as detailed in the New York Daily News and on "60 Minutes"? McGwire injecting Jason Giambi? Canseco introducing steroids to teammates Juan Gonzalez, Rafael Palmeiro and Ivan Rodriguez while all were on the Texas Rangers? And the latest round of allegations in early bootleg copies of his book, implicating players from Roger Clemens to Bret Boone?

Pathetically, all the titillating, damning stuff in his upcoming book, "War and ... ", er, "Juiced: Wild Times, Rampant 'Roids, Smash Hits and How Baseball Got Big," are now in the realm of possibility.

We've learned too much about the sordid, steroid side of baseball in recent years to summarily reject the message because of the messenger.

McGwire defenders, led by Tony La Russa and many former Oakland teammates, have flooded out of the woodwork. But one thing is becoming apparent in this incredibly messy, but still-growing steroids crisis:

You just don't know whom to believe anymore. Too many people have a vested interest in lying, or covering up, or sweeping away the truth.

We couldn't believe Giambi when he denied, repeatedly and by rote, all the steroids allegations, right up to the moment he raised his hand to a federal grand jury and swore to tell the whole truth and nothing but the truth.

We couldn't believe Canseco back in 1988, when he vehemently denied Washington Post columnist Thomas Boswell's assertion on national TV that Canseco was "the most conspicuous example of a player who has made himself great with steroids."

Boswell also said that American League players called steroids a "Jose Canseco milkshake." Back then, Canseco called the charges "really ignorant, not true and very slanderous" — remarkably similar to what players and management are saying today about Canseco's charges.

Is Canseco telling the whole truth now? The sad part is, we may never know, not definitively. Maybe some innocent people are getting tarnished unfairly, which would be shameful. But even Dave Stewart, in the course of a scathing indictment of Canseco in a San Francisco Chronicle interview this week ("The guy was poison. He was weak-spirited ... "), added this aside:

"If this is all made up, he'll suffer some serious damages. But if you're an admitted steroid user, believe me, you'd know who uses them."

Let's check the scorecard: We now have three former MVPs linked definitively to steroids: the late Ken Caminiti, who confessed to Sports Illustrated in 2002; Giambi, who allegedly came clean to the grand jury in testimony leaked to the Chronicle and not disputed by Giambi; and Canseco, who, according to the book description put out by publisher Regan Books, "mixed, matched, and experimented to such a degree that he became known throughout the league as 'The Chemist.' "

We have two other MVPs, Gonzalez and Rodriguez, now linked to steroids circumstantially through Canseco, along with a member of the exclusive 500-homer club, Palmeiro. We have the two home-run kings, McGwire and Barry Bonds, under increasing steroids scrutiny. And we have an entire power generation from the 1990s and early 2000s, including Boone, smothering under the same cloak of suspicion.

As for Canseco, I called Dave Henderson, the normally blunt Mariners announcer who was a key player on the Oakland A's in the Canseco/McGwire era. Uncharacteristically, Henderson declined to comment on the upcoming book and Canseco's allegations, saying that he didn't want to help his former teammate make a penny off his book.

But Henderson had given a hint of his feelings about Canseco in an interview with me when Canseco announced his retirement in 2002.

"I think we were fine, as teammates, until he got lackadaisical on the field," Henderson said then. "That's when we had our problems. Eventually, that's why he was traded. We all said, 'Get him out of here.' "

That goes with the portrait of a selfish, undisciplined player emerging from comments by La Russa, Stewart, Terry Steinbach, former Rangers general manager Tom Grieve ("You've got a guy who has squandered a fortune, his personal life, is an embarrassment and he probably has no way to earn an honest living. He's a joke.") and virtually everyone else who has commented in the last week.

But that hasn't stopped Canseco's allegations from sweeping the nation, and it hasn't stopped his book from shooting up to No. 17 on Amazon's sales rank Friday — four days before it was to be released, with a "60 Minutes" boost today.

Baseball, no doubt, is going to have to endure these steroids eruptions all season. It is the price that must be paid for years of benign neglect of the entire issue. Players like Boone, whose body — and statistics — got conspicuously bigger will have to endure shots like Canseco's, even if the growth was achieved entirely in the weight room.

Canseco's insinuation that Boone used steroids is particularly tawdry, because unlike most of the others he throws under the bus in the book, he claims no personal knowledge of actual steroids use — just supposition and innuendo regarding Boone's inclusion "in the club."

But the damage has already been done, as with all the other charges hurled throughout the book. They all might be nothing more than the ramblings of a deluded mind.

But a gnawing — and growing — doubt remains: they might not be.

Larry Stone: 206-464-3146 or lstone@seattletimes.com