One of the downfalls of getting a paycheck raise is getting used to a more expensive lifestyle. This is actually a bad habit of employees. Most of the time, the first thing that they do when they get a raise is to upgrade their lifestyle. This can be dangerous especially when a financial crisis happens. You might find it hard to adjust and make sacrifices in case your money runs out on you.
Another negative effect of a salary increase is being too self-satisfied. This may be a positive but too much of it, especially when it comes to money, can be a bad thing. For instance, you may be too comfortable about the money coming in that you stop monitoring where it goes. This can be dangerous because you might be spending too much already or racking up too much debt. If you fail to monitor it, you might be in a big financial trouble and you are still unaware of it.
I would bring my answer to an end by the following quote:

Excess of everything is bad.


Perfect Money/Payeer/Epay/Neteller: