Treating the share market like a casino can be a risky strategy.

Sure, you might win a couple of times here and there, but the house generally wins in the long run.

While there is nothing wrong with having the odd speculative bet from time to time, it’s not something that investors should spend a great deal of time on in my opinion.

With that in mind, here are four shares that I think investors should think twice about before ‘doubling down’ on:

Slater & Gordon Limited (ASX: SGH)

Shares of the embattled law firm have plunged around 95% over the past 18 months and, in the process, wiped out around $2 billion worth of shareholder value. If that wasn’t bad enough, Slater & Gordon is now facing its own legal battle against investors who feel they have been misled by management. Even if the company can get its business back on track, prospective investors are unlikely to be reaping the rewards anytime soon.

Cash Converters International Ltd (ASX: CCV)

‘Cashies’ is probably one of the most loathed shares on the ASX and this has certainly been reflected in its share price performance over the past few years. A number of legal disputes, the termination of bank relationships and an underperforming UK division have all detracted from the good performance of its Australian business. Although Cash Converters is taking steps to rectify all of its issues, it remains a stock not for the faint hearted.

Fastbrick Robotics Ltd (ASX: FBR)

Fastbrick Robotics has shot to fame thanks to a massive surge in its share price. The shares started August at 2 cents a piece and hit a high of 16.5 cents just a couple of days ago – a rapid gain of 725%! Despite the impressive gain, it would be fair to say that the robotic brick layer is still selling a dream, considering it generated revenues of just $298,000 in FY 2016 and a net loss of $5.8 million.

Resapp Health Ltd (ASX: RAP)

ResApp is another company that has shot up to fame this year thanks to a 940%+ gain in its share price. The digital healthcare company claims to have developed technology that enables health care professionals to diagnose respiratory conditions with just the use of a smartphone. There is no doubt the technology could be game changing, but I find its $300 million valuation a little hard to swallow, considering its last financial result showed revenues of less than $83,000 and a net loss of more than $3.2 million.

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Motley Fool contributor Christopher Georges owns shares of Cash Converters International Limited. The Motley Fool Australia has no position in any of the stocks mentioned. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy. This article contains general investment advice only (under AFSL 400691). Authorised by Bruce Jackson.