Are you tempted to go out and tell the world how much better you are than your competition? I'm sure you can list many reasons you are superior than your competition, and that's good - but, try to keep those items on your sales kill sheet and out of your marketing material. If you want to deliver effective marketing, you need to have a positive message.
First, let's take the big dog example. How do you think an advertisement by McDonald's would be perceived if they talked about how much cheaper and faster and closer to home they were than Bob's Burgers? You'd laugh, but why? Big dogs look pathetic when they compare against any competition. Big dogs can't even market against other big dogs without becoming a mockery. Remember the Pepsi Challenge? If you don't, it was marketing by Pepsi comparing directly to Coke. It was effective in that people remember it, but it has become a lasting mockery of their product rather than a branding moment message.
What if you're the little dog? Can Bob's Burgers market with a message that tears down McDonald's with all the negative things attributed to their products and service? (I couldn't list them here, but I'm choosing not too.) Think about it. Would you eat at a place that has an advertisement that says the equivalent to, "We're better than garbage, so eat here!"? No, you wouldn't. You really wouldn't.
Some of those negative facts or "we're better" comparisons have a good home on sales kill sheets. You can bring them up in small group conferences with clients who are directly comparing you to your competition when making their purchasing decisions.
Coupons and sales work this way too, but that's really a sales tactic than marketing message. You are making a sale, because person X has a coupon to McDonald's and not to Bob's Burgers. You don't want your primary marketing and branding messages to be "we're the coupon people!". You can never escape that persona once you embody it. Just ask J.C. Penny's. I see this happening with McDonald's mobile app. Their mobile app offers free sandwiches and many bogo offers. That's driving immediate sales on a large scale, but is it really the longer term experience they want their customers expecting. They are training their customers expect discounts on an already industry leading price point. That customer habit will be very painful to undo.
Back to the positive message! You want potential customers to take action and engage with your business. As any good leadership training will advise, empower and encourage. Your marketing message is an opportunity for you to be the leader. Let your customers feel empowered, so they want take action and feel engaged. Your goal is for your customers to take action, be engaged, and protect your brand reputation. Maintain a positive message, so that your marketing will be effective for the long term.