Ever is probably an over-reaction, but in general these types of naming conventions just don't make sense. How is tblInvoices easier to understand than Invoices? How is it more clear? Further, when you get hit by a bus, what does it communicate to the next person who takes over your job. I just do not see it.

I'll give you an exception I have used and that's for lookup data. You know, the little name/value pair tables that are just there to enforce select lists? On those I've used c_TableName. The 'c_' stood for Code tables. It served two purposes. It made them all group together within SSMS, and it differentiated these tables from real system tables.

However, now, I wouldn't even do that. I'd put them into a separate schema but with standard names. It would serve the same purpose but improve the overall readability. Instead of c_ which means nothing unless I tell you what it means, I could use Code.TableName or Lookup.TableName which makes things more clear.

Naming standards should improve clarity and communication. Specialized abbreviations just don't add to the clarity. In fact, they tend to reduce it. But, this is one of those things that comes down to preference, not a technical reason. So if it works for you, go for it. But it's not a standard I'd support given the choice.