Can you turn a white alfredo sauce into more of a spicy pasta sauce successfully?!

Depends which direction you want to go. If you want to keep the same flavor but simply want spice, I would add cayenne pepper, spicy, but not much flavor. Another option would be to fry up some curry powder with oil and onion and garlic then add it to the sauce. If you want a more cajun feel you could add cajun seasoning and diced tomatoes for a creamy tomato sauce.

I completely agree with the 1st poster. A curry would go very well. I have had a very interesting curry cream sauce over a pasta in the past. The only difference was my curry cream did not contain cheese. But, I still think it would work.

And, the cayenne would also work.

I have also combined alfredo with a red sauce and spiced it up a bit with hot pepper flakes. It was sort of like a spicy vodka sauce.

Add the premixed spices that you can buy in the grocery like roasted Red Peppers and Garlic or Lemon Pepper..
Just take a look at the spice section to see all the variety available.Cheeses added to the Alfredo Sauce such as blue cheese or Feta cheese. They all will change the taste significantly, in a good way. It's just a matter of taste.

Ewww! No! By making Alfredo sauce spicy, you will mask the delicate flavors of the cheeses, which are the basis of its flavor. About like adding hot sauce to milk!

add red pepper flakes
or cayenne pepper
to it