If you find yourself cringing at your spouse's clothing choices, and have not been able to convince him to change his fashion sensibilities, you may want to take over clothes shopping entirely. However, you want to do so with enough tact as to not hurt his feelings. In fact, you want him to be happy about it!
Buy your husband an inexpensive but flattering shirt for a birthday or holiday present.
Tell him how good he looks in the shirt. Name a specific reason the shirt looks good that subtly contrasts with his current clothing choices-- for example, if your husband habitually chooses shirts in loud, unflattering colors, you might say, "You look really good in that shirt. That shade of green is perfect for your eyes".
Come shopping with him the next time he needs new clothes. Help him pick out clothes that you like. Be sure to tell him how good he looks in those clothes.
Suggest that you do the shopping run yourself the next time he needs new clothes. Say it casually, and suggest something that he could do during that time.
'Phase out his solo clothing shopping expeditions.
You can slowly replace the former wardrobe by getting him to use the less flattering clothes as "yardwork" or "home improvement" clothes. As these clothes fall prey to stains and tears, they can be replaced. Plus, this keeps the new clothes from becoming sacrificial items.