In my eyes, one example of good design is in Bath and Body Works' body wash line. Each different scent is packaged uniquely, and each design is visually attractive, typically targeting a female audience. Each individual scent of body wash is packaged in a bottle uniquely designed to portray the "flavor" within, almost in a way that one might be able to even guess what the soap will smell like without actually having to smell it. But Bath and Body Works haven't just designed the bottles to illustrate a scent - they also put a pigment in the soap itself to further convince customers. For example, what smell would you guess a pink a flowery bottle with pink soap might have? To me, I would automatically imagine something sweet and light. A darker soap might illustrate a richer, deeper smell, maybe even more "mature".
Take a closer look at Bath and Body's scent line Japanese Cherry Blossom. This scent has a very attractive design and color. The flower designs are placed carefully on the bottles to lead the eye around, almost drawing the customer in. The flowers are not centered or whole. The design is run off the bottle, allowing the viewer to complete the design in their own mind, relating to Gestalt's Law of Closure. A big law used in this picture is the Law of Similarity. Each scent line (body wash, lotion, body spray, etc) has a very similar design. Japanese Cherry Blossom's soap versus body spray is by no means identical, but with the use of similar colors and designs and the use of the cherry blossom flower, customers know that these products belong the the same group, and have the same smell.Back to the body wash/ shower gels, these bottles not only look good in or out of shower as a display or decoration, the design of the bottle functionality itself is convenient, with that handy little pop-open lid. Overall - a definite go-to design.
Irish Spring
One great example of terrible design is shown in Irish Spring's body washes. This is a product that I would never, ever buy. It looks cheap enough to make my skin fall off if I were to use it. The design is very boring. The shade of green is incredibly unattractive when thinking of washing your body with it. My first thought when I look at it is of the Hulk...which although is an awesome superhero and a fantastic movie...the Hulk does not bring "clean" and "smells good" to mind. Irish Spring also makes me think of bathroom cleaner! It screams "harsh chemicals". Like that stuff you would put in your toilet. I haven't even bothered smelling their soap products because the design is so unattractive to me. The color isn't the only bad thing about this design. The text font and direction is also bad. There is not enough variation to produce any interest from viewers. Each different scent of body wash is identical in design and color. It's all Hulk green. Then it looks like they taped this random little box that is describing what scent is inside, but it does not work well with the rest of the bottle design, like wearing mis-matched clothes. "Ice Blast's" box does not match or compliment Irish Spring's bottle. 
I think if Irish Spring were to use more variation in their design (and a lot less green), their product would be a lot more popular. I might consider "Icy Blast" if the whole bottle illustrated a minty feeling. On the right is another bottle by Irish Spring, "Signature for Men". I think this design is slightly better than their other more original bottles. The color is more cool and relaxing, and the sticker on the front is way more appealing. Even the lid looks better. If it weren't for that ugly "Irish Spring" stamp at the top, this product would have an acceptable design. 