If a bad guy controls a CA that your computer trusts (e.g. because it was installed as a root CA on your machine), then that attacker does not need to rely on anything as crude as a typographically similar name; he can make a fake certificate which says "gmail.com" in all its details, and claim to be certified by VeriSign, the Food&Drug Administration, and the Pope. Root certificates are said to be "root" because they really are at the root of your trust.
You could try to get some external validation; for instance, you could try to phone Google's headquarters, ask to speak to a sysadmin, and see if he could spell out to you, over the phone, the "thumbprint" of the certificate. You could then compare it with what you see on your side; this would detect foul play. However, this assumes that the phone is "intrinsically secure" (a rather dubious assertion at the best of times), and also that you will find at Google's a sysadmin with enough free time and humour to actually respond to such a request.
A more fundamental issue is that if some attacker could plant a rogue CA in your computer, then there is little reason to believe that he stopped there. Manipulating the trust store requires administrative rights; the same attacker could have installed a key logger or other kinds of malware. He could even do it afterwards because normal software updates are signed: with his rogue CA, the attacker could fake-sign some fake updates full of nasty code.
Thus, usual wisdom are that if you suspect that your root CA have been manipulated, then you cannot really salvage your machine except with a full format-and-reinstall of the operating system (and, even then, this cleanses the machine only if no virus has been installed in the flashable parts like the BIOS and the firmware of some peripherals).