First of all, there is no such thing as being too "poor" or too "financialy straped" to visit WDW. As long as you aren't skiping the mortgage and car payments in order to go, knock yourself out. If all you can manage is 4 nights at a Value and need to split meals, then that's what you do. I do think making a salad out of the toppings bar is an abuse, but beyond that, to each their own. Personally I'd just cut a double cheesburger in half rather than buy an extra bun, if I need to save money that much then I'll save the 79 cent for the extra bun, too! I did hear once of a woman that brought her own extra buns, since you can buy an 8 pack for $1 anyway!
As for the "dirty" diaper in the stroller, while it is a cleaver idea, I personally would figure out another solution, but hey, if it works for you, have fun! In fact, if you really want to go for shock value and keep the theives away, try a bit of melted fudge...
"Swaping" items I think is quite clever. DH and I own two Pal Mickeys and don't use them at home. We consider them souvineers but I can see how some people want them just for the park. Why not split the cost between several families? As for strollers, again, why pay more than you have to if there are people will to share?
Pool hoping. First, it's not pool hoping you're going between sister resorts (POR and POFQ are "sisters", and guests at either can use pools at either, for example). Beyond that, it is wrong and against the rules, but I personally can care less. Just remember, if you do it, you're racking up bad Karma!
Mug refills. While I do feel that anything against stated or posted rules is wrong, again this is an issue I personally could care less about. I don't get mugs anymore, nor do DH and I eat in the food courts so we don't witness it anyway. Is it wrong? Yes. Is it the worst offense on the planet? Not really, but again, you're racking up bad Karma (see above) so don't be surprised if for every refill you steal, something minor but anoying or frustrating happens to you in return!

WDW will eventually put a stop to it with the bar codes, they've already done it at the water parks, it's just a matter of time for the resorts. I'm willing to bet the $$$ it would take to set up a bar code system is way more than what they'd save in people mis-using the mugs.
As for the extra people in a room, sorry, I don't give anyone a pass on that. The hotel industry, for whatever reason, has made the "family of four" the standard in which they operate. If they drew the line at five, then families of six would be complaining. If it was six, families of seven would be slighted. The line must be drawn someplace, and for the most part, it's 4 people. Disney has many options for families of 5 or more. POR has rooms with trundle beds that will sleep 5 that, in many cases, is cheaper than two rooms at a value. You also have the option of getting a room at one of the deluxes that sleep 5, a Wilderness Cabin, a two bedroom villa, or go camping at the camp ground. Even if you decide that two rooms at a value is the best fit for your family, you may be paing for an extra room but you also get twice the space, twice the bathrooms, and the ability for people in one room to be awake and active while others can sleep in peace in the 2nd room. In otherwords, you are getting more for your money. WDW has listened, and from what I understand is puting in suites at the All Stars, so yet another option for larger families will be available soon. And after all of that, if you can't, for whatever reason, afford a room that fits five or more at WDW, you can always stay off-site at a hotel near WDW that sleeps as many people as you need. Heck, you can rent a whole house for a week for what a moderate can cost!
And by the way, I grew up in a family of five. We managed to travel at least once a year (sometimes several times of year) just fine, including a trip to WDW. So no whineing about how "I don't know how difficult it is to have a large family". Sorry, I've been there, done that and DO know. Go tell your sob story to someone else.