The readers speak out this morning on products or offers they've recently run across that just might be a little less tremendous than they're cracked up to be.

From Owen Remington of Lancaster, Va., comes a check for one dollar sent to him by the Hot-Line Credit Card Bureau.

The check is real, too -- not one of those vouchers printed up to look like a check that you can "cash" only by driving 17 hours to beautiful, glorious Ripoff-by-the-Rappahannock.

When Remington noticed the word "negotiable" on the front of the check, he thought it had to be his lucky day. But a little birdie told him to read the back. There, in type about one-third as large as the "ONE DOLLAR AND 00 CENTS" printed on the front, was the hooker:

"Negotiation of this check represents acceptance of a six-month free membership in the Hot-Line Credit Bureau of America. After six months, my Hot-Line membership will automatically continue . . . for only $1 a month."

Next, from Ted Namey of Clifton, Va., comes a flyer mailed to him by the Parker Publishing Company of West Nyack, N.Y. The product Parker is pushing is a new $12.95 book called "Mental Dynamics." The purpleness of the prose speaks for itself:

"Here are five simple actions that will make you a Mental Wizard (italics Parker's) -- Three times as smart as you are now, in a single weekend!"

"I've been retired for 18 years, so I figure this won't do me any good," Ted writes. But how much good could it do anyone? If you're dumb enough that a book can help you get three times smarter in one weekend, it's amazing that you haven't walked in front of a bus long ago.

Finally, two samples from the mailbox of Bill Rhodes of Berwyn Heights.

The first: An ad for mail-order "uppers," from Mid South Pharmaceutical, Inc., of Hixson, Tenn.

"Don't let the 'blahs' get the best of you," says the Mid South blurb. "FIGHT BACK with an extra boost!!"

The fine print reveals the boosting product to be ephedrine sulfate tablets, which may be sold without a prescription, but which also are capable of causing "excitement and insomnia" if abused, as Mid South's literature points out.

What the literature doesn't point out is how Mid South intends to keep teen-agers or known drug abusers from placing orders.

The second eyebrow-elevator in the Rhodes mailbox: a solicitation from Better Living magazine of New York, offering a lifetime subscription for the "incredible" price of $2.95. "How can you lose?" asks a letter from the associate publisher.

Here's how. Down in the fine print lies this paragraph: "When today's high interest rates drop appreciably -- and some experts think this may be soon -- this offer will be withdrawn automatically."

What does "appreciably" mean? Could the drop have happened already? Better Living doesn't say.

None of this is to suggest that these companies are committing crimes or deliberate misrepresentations. It's only to remind readers of consumerism's Rule One: If it looks too good to be true, it probably is. The rule didn't achieve its ranking for no reason.