@Jay Hinrichs Actually, there are several things asset protection attorneys and professionals can do to prevent this "alter-ego" problem.
First is structuring the entity properly. Traditional LLCs are much more likely to be "pierced" because of pooled assets. SLLCs are slightly more secure and there's very little case law on them precisely because they are tough to fight. Setting up entity properly means not going it alone--your lawyer is the one who can help you make decisions about whether you want a single- or multi-member, whether passing through for taxes is in your best interest, etc.
Second is utilizing it properly--which means it's a good idea to check with your attorney before transferring anything into or out of the SLLC structure.
Third is securing your anonymity. We like to do this with a Land Trust, and have written about this process of disguising company ownership before here on BP. What you might not be aware of yet is that you can actually pair a Land Trust WITH a SLLC to completely remove you (as an individual) from the picture. The Anonymous Trust will be listed on state filings. Trusts are three-part documents that, if structured correctly, will be filed privately. Names aren't under obligation to be reported to the state. So if someone comes to sue you, they will see the property is owned by Series (A,B,C,whatever) and that the structure is owned by XYZ Trust. Your anonymity is vital, and land trusts can also protect you and your investments from identity thieves.
Finally, you have to do your part to maintain these structures. That means not co-mingling operations and assets. The companies that hold your assets (Series in the case of the SLLC) should NEVER do business with the public. That's your shell company's job. In fact, if someone comes after you, the shell company is the fall guy. That's the one we want them to sue, because it owns nothing.
I hope that has helped clarify some of your concerns.