There's a word for that: arbitrage.
Pure arbitrage is not allowed and will get your accounts banned. Pure arbitrage is defined as where your landing page has little content and exists only to get visitors to click on the ads. If you think about it, the economics just don't work or make much sense. You will never pay lower for traffic than the average revenue generated by those visitors clicking.
If you have a quality blog with some Adsense, nothing wrong with that. Just don't expect to make more money from Adsense than the cost of Adwords. What you want to use Adwords for in this case is to advertise your blog, make people aware of it. If it's of quality, they'll come back and some will click ads. But don't expect a long-term profit with this method. The idea is to get people interested, initially paying for them, and continue providing them with great content with enough revenues from Adsense to pay for costs. You will not make a living from this.