By global standards, very few Palestinian refugee camps are truly "squalid" by global standrads--in most places (Syria, Jordan, the West Bank) only a minority of refugees live in the camps, which have simply become low-income housing areas. Refugee incomes and standards of living in those areas are equal to those of the non-refugee population.

Gaza is slightly different because it is overcrowded, much poorer, and most of the population are refugees.

Lebanon is even more different still because refugees have, in the past, been barred from using government social services, from working in most professions, and even from owning property. (The Siniora government would like to change this.) Moreover, ever since the civil wars refugees have tended to cluster in camps for security. All of this reflects the enormous demographic and political sensitivity of the refugee issue in Lebanon, where the constitution explicitly forbids permanent settlement of the Palestinians there.

UNRWA--the UN agency that deals with Palestinian refugees--generally does an excellent job, as the social indicators suggest. (Donors have sometimes criticized the agency for budgetary planning and management/reporting issues, but not for corruption and waste.)

Gulf money financed the reconstruction of destroyed refugee housing in Jenin and Rafah/Khan Yunis (Gaza)... I suspect it will be the same in Nahr al-Barid.