It is a very modern idea and there are lovely red dresses. If you feel uncomfortable, try incorporating a theme to help. "Roses are Red" or "Queen of Hearts".
Now I believe weddings are more about what the bride and groom want versus what is proper etiquette. Proper etiquette would probably frown on a red wedding dress. If it is what you want, for it.
i thinking the asnwer to this question is know the etiquette is a white dress it mean white and that there was no sex between the to people getting married