Is a "lie of omission" dishonest?

[Sarkus]

Indeed - we wish to be open to ideas while also adhering to a reasonable standard of evidence. It is, in my experience, inevitable that members will become aggressive and aggravated when legitimate, relevant evidence is simply "hand waved" or outright ignored during a discussion.

If evidence is presented then to ignore it for any reason is discourteous.
If it is ignored because it is deemed to be irrelevant then it should be explained why it is thought to be so, in that way you at least acknowledge the existence of the evidence. To do otherwise is discourteous, but I do not think that this would be dishonest.

If, however, it is ignored to deliberately avoid being shown to be in error, or because it works against your own position, then it I would consider this dishonest.