Red Flag #1: Proprietary Blends Hiding Ingredient Doses
A proprietary blend lists multiple ingredients under a single combined weight — for example "Performance Blend 1,200mg" containing twelve separate compounds. The label discloses the total blend weight but not the amount of each individual ingredient.
Why this is a problem: an ingredient at 10mg and an ingredient at 1,190mg can appear equally on a proprietary blend label. The format makes it possible to include impressive-sounding ingredients at token amounts, too small to matter but enough to put on the label. We treat undisclosed doses as a negative in our reviews and say so when a product we cover doesn't list them.
Red Flag #2: Dose Mismatch with Published Research
The second most important red flag is the gap between the dose of an ingredient in the product and the dose used in the clinical research cited. KSM-66 ashwagandha trials mostly used 300 to 600mg a day, so a product with 150mg is unlikely to match those results. NMN trials have used roughly 250 to 1,250mg a day, so a product containing 50mg is well below anything tested, regardless of how prominently NMN appears on the label.
Red Flag #3: No Money-Back Guarantee
A clear money-back guarantee lowers your risk, although it isn't evidence that a product works. Most supplements we review carry a manufacturer money-back guarantee, but the length and conditions vary (some cover only unopened bottles, and most don't refund shipping), so check the exact terms before you buy. Our guide to supplement money-back guarantees explains what to look for. Products with no clear, written guarantee deserve extra caution.
Red Flag #4: Exaggerated or Specific Medical Claims
Under FDA rules, dietary supplements cannot legally claim to diagnose, treat, cure or prevent any disease. Products making specific medical claims — "proven to cure X" or "eliminates Y permanently" — are either regulatory violations or examples of deliberately misleading marketing. Legitimate supplement brands communicate benefits in terms of support, maintenance and general wellness.
Red Flag #5: No Disclosed Manufacturer or Facility Information
Legitimate supplement manufacturers disclose their identity, location and manufacturing facility details. cGMP certification from a named, verifiable facility is a positive signal. Products with no manufacturer address, no facility information and no way to verify production standards should be avoided entirely.
Red Flag #6: Sold Exclusively on Third-Party Marketplaces
If a supplement is only available through Amazon, eBay or other third-party marketplaces — and has no official manufacturer website — this is a significant warning sign. Legitimate supplement brands maintain direct-to-consumer sales channels specifically because they want to control product authenticity and offer money-back guarantees they can honor.
Red Flag #7: Before-and-After Photos Without Context
Dramatic before-and-after transformation images in supplement marketing are almost universally misleading — often showing different lighting, posture, hydration status or simply paid models. Results presented as "typical" that reflect extreme outliers are a form of deceptive advertising. Look instead for brands that describe realistic results and, where one exists, point to a published trial of the product itself.
What Good Looks Like
No product ticks every box. VigRX Plus and Semenax have each been tested in a small, company-linked placebo-controlled trial of the product itself, but neither lists per-ingredient amounts on its sales page. Testosil discloses every dose and posts a third-party lab certificate, but has no trial of its own and provides 300mg of KSM-66 per serving, half the daily amount used in the main trials. All three come from an identifiable company with written guarantee terms. That's the checklist worth applying to any supplement: what was tested, at what dose, who makes it and what you can get back if it doesn't suit you.