I don't decide where to spend my advertising dollars based on the company's stock price. I do a trial run and see if the CTR and conversions come under my customer lifetime value. If it does, then I pump more money into the ads. No where does stock value come into the equation.
I couldn't care less if the company is dieing - as long as I'm gaining more money (in terms of LTV of new customers) for less money than I'm spending on ads, it's a win to my business.
If the company goes belly up...well I just move my advertising budget somewhere else.