Shopify (NYSE:SHOP) was crushed by allegations it was little more than a get-rich-quick scheme. Shares that had nearly tripled over the past year have tumbled 20% since the critique broke in early October. That naturally leads an investor to wonder whether the e-commerce storefront will overcome these charges and make its stock a buy, or they'll prove true and buying now will be like catching a falling knife.

What we know

Famed short-seller Andrew Left at Citron Research issued a scathing rebuke of Shopify, alleging the platform routinely violates FTC marketing guidelines and was "dirtier" than Herbalife (NYSE:HLF), the multi-level marketing company that was required to pay a $200 million settlement with the regulatory agency.

Websites spring out of computer monitor

Image source: Getty Images.

There are several aspects to Left's accusations. On the one hand, he contends Shopify is violating FTC regulations by promising people if they use its product they could become millionaires. He also says people promoting the service aren't disclosing they're being compensated for their endorsement by the outfit. Although other, larger marketers may also do something similar, it's still an illegal activity, similar to Herbalife, which was slammed by the FTC for advocating "members can 'quit their job' or otherwise enjoy a lavish lifestyle" by using its products. Left says Shopify even has a form letter on its website that platform users can use to send to their bosses when they quit their jobs.

Comparing the company to Herbalife seems to fall short, since people aren't directly selling Shopify products like they do with the supplement distributor; users are using its platform to sell their own goods and services (Left does note bloggers and other sites can make money referring people to Shopify, and notes that is akin to affiliate marketing rather than an MLM scheme).

Still a good value?

There appear other, more problematic accusations that Shopify will need to address. The Citron report has a lot more teeth when it accuses the company of being highly overvalued. At 20 times sales, it is valued about twice as much as other leading SaaS companies like (NYSE:CRM) and Workday (NASDAQ:WDAY), and Left contends Shopify's far richer than it has any right to be considering there is little known about the vast majority of its 500,000 customers.

He also notes that only 50% of Shopify's revenue comes from subscription fees while other, better SaaS businesses are reporting 85% of their revenues come from subscriptions. Left notes Shopify is an $11 billion business trading at nosebleed valuations. He suggests the stock could and should sit at about half its current price and then still have much more room to fall if and when the FTC gets involved.

Man holding head in front of stock market chart crashing

Image source: Getty Images.

The dust is still settling

In cases like this, there is often a lot of confusion, and Shopify posted a note on its website stating "We vigorously defend our business model and stand resolutely behind our mission and the success of our merchants."

The platform provider offers its customers the tools they require to meet the needs of consumers who expect to be able to transact anywhere, anytime, on any device. There's a lot of blowback from analysts and customers to the Citron critique, saying it is way off-base.

With the company reporting earnings at the end of the month, it may be that its actions will end up speaking louder than Left's words. The short-seller has been right before, and his point on the company's valuation certainly does have some merit. For cautious investors, I'd caution against jumping into the stock just yet.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.