Yes, it's a bad practice for two reasons:

1. Prefixing a unused variable with an underscore isn't a widely accepted standard. It will likely be ignored the "uninitiated".
2. I've seen some people prefix private member variables with an underscore, and your standard would greatly confuse such people.

Yes, it's a bad practice for two reasons:

1. Prefixing a unused variable with an underscore isn't a widely accepted standard.* It will likely be ignored the "uninitiated".
2. I've seen some people prefix private member variables with an underscore, and your standard would greatly confuse such people.

• 2023 Update: C# is now promoting the discard placeholder variable: _.