If Google has it, are you seriously worried about what some random spammer might do? It reminds me of that line in Alice's Restaurant where Arlo Guthrie responds to the sergeant at the draft board regarding his questioning the morality of a litterbug.
I use Google voice. I also assume that Google has reasons for offering the service that go way beyond wanting to help humanity by giving them a free or dirt cheap means of communication. My privacy is a thing of the past. It might help if you use a pseudonym with your gmail account and false personal information. Though that only makes you slightly less transparent. The minute you used your credit card to get your $10 voice credit, they nailed you.
That said, I don't think spam is a major issue with gmail if you pack your account with every kind of anti-spam, anti-ad, anti-malware, and anti-tracking device available and don't use your primary account for commercial dealings or give it to anybody outside of personal friends. I have had a gmail account for years, take all those precautions, and have been almost completely spam-free. My other gmail account that I use for non-personal stuff (eg transactions) , on the other hand, is littered with spam.
The potential privacy issues regarding companies like Google and all the information they mine go way beyond spam. We have to realize it's a new world in that regard, and, knowing the potential benefits of the services provided, learn to come to terms with it (and the serious risks involved) the best we can. That probably makes a lot of sense to people here who are involved in investing and experienced in making risk/reward decisions , accepting a lot of lack of transparency re: Wall Street.