If you have enough problems and your laptop is still under warranty, they will replace it with a brand-new laptop if you yell at the enough. Furthermore, bad laptops are the exception and not the rule with Dell, so you probably have nothing to worry about.
If you call a refurbished laptop "new" then yes, they will.
You're right about the overall quality of their laptops. In general they do last a while before you need to fix them. But what you're missing is that after about a year they stop carrying new, non-refurbished, parts for the Inspiron series laptops and, therefore, will only have refurbished parts in stock. Therefore, any laptop you receive as a replacement after that initial year or so will be refurbished.
This information comes straight from Dell. All I'm trying to say is that the Latitude series are professional series laptops. And, as such, are designed from the ground-up to be better than the Inspirons. They are more durable and they keep new parts in stock for years after they product has been released. The reason they do this is so they can provide multiple tiers of laptops for consumers. Inspirons are low-end (IE el cheapo), Latitude are Mid to high-end, and the Precision Mobile workstations are the ultimate and carry certifications to prove that they comply with industry standards.
A couple of years ago, my parents purchased an Inspiron laptop that shipped with a bad BIOS version that prevented the cpu fan from activating correctly. The processor would overheat and the computer would constantly freeze. The same year, the company I worked at ordered 100+ latitude laptops (different orders and shipments) and none of them had any problems when they arrived. The fix for the faulty BIOS was simple, but it gives you an inseight on the quality contol they have over the Inspiron series versus the Latitude.
If you do manage to get your hands on a replacement "brand new" non-refurbished Inspiron, sent to you from Dell, AFTER they stopped carrying new parts for it, then it is most likely a different model than the one you purchased. Therefore, if the new laptop is given to you under your previous warranty, then it's a breach of your warranty contract since your warranty only covers the parts in the laptop you purchased.
Lol, this comes form 5+ years of previous experience working with and supporting various laptops from various different manufacturers. I'm just trying to provide insight into Dell's madness so that others can make informed decisions. Like I said before, if you doubt me, just call Dell and ask them. If I'm wrong I'll eat crow and admit it.