Is it safe to buy using your credit card on Facebook apps games like Restaurant City and Mob Wars?

[No to Bullies Yes to Love]

Using the Paypal and Credit Card shopping in Facebook apps like Restaurant City: is it safe?
I am currently playing a few games in Facebook and my friends had me hooked on Restaurant City. I'm not too addicted but I would like to purchase more points buy buying $ 4.99 worth of points.

I would like to know if using the credit card and paypal option in Facebook application games are safe and has anyone here had problems or issues in using it?

Please serious answers only. I posted this question before and got a lot of crappy responses
Where do i get those refillable cards?
As for the responses, they respond in non serious, crappy often insulting tones. hats what I meant