I agree that appearances can be deceptive.
I have two friends that I initially thought were both extremely well off, but as I've got to know them more, I've found out the following:
Friend one has three children at private school, always looks beautifully dressed, at least one foreign holiday per year plus lots of mini breaks both in the UK and abroad, and a massive, well decorated and furnished house.
It turns out that her grandparents pay the school fees for her eldest child, her parents pay the school fees for her middle child, and her in-laws pay school fees for the youngest! They bought their massive house relatively cheaply, and have a low mortgage as grandparents gave them money when they bought their first home. The house is furnished with good quality secondhand furniture, Ebay buys and items from outlet stores. My friend buys all her clothes on Ebay and sells things on there too. Foreign holidays are usually booked last minute through budget websites, and they shop around for deals for other mini breaks. Oh and they always, always shop at Aldi, never any of the pricier supermarkets. My friend also always has beautiful nail extensions, and it turns out that a mobile therapist visits her house once a fortnight and only charges her a tenner each time!
Friend two has four children and she and her DH do jobs that pay average wages (he works in a call centre, she works in a shop), a massive 6 bedroomed house, they have nice holidays, nice clothes, and seem to eat out a lot.
She's told me that the reason they have a big house is because they inherited money from her parents, therefore have no mortgage. They also 'stagger' their working hours, hence they have no childcare costs. She works mornings and her DH always does the 2pm-10pm shift at work. She is also an Ebay fan, and kits the children out from there or in the Next sale, and sells loads on there too. As soon as the kids have grown out of anything she lists the clothes on Ebay straight away.