You are attending a lecture by a banker and you expect her to advocate bank savings accounts. However, she advocates stock investments instead. Since her message goes against her own self-interest, you perceive her as and the message as .

sincere; persuasive

Explanation:

Since her message of the banker goes against her own self-interest, you perceive her sincere and the message as persuasive.

Being sincere simply means that the banker is giving the lecture genuinely and what she is saying is free from being deceitful. Also, hee message is being regarded as persuasive.