I take care in who I let to now and I am actually willing to take a slightly lower rental or to hold rental increases for a valued long term tenant. Eventually though rents will still be increased if ROI is to be maintained. One of my current tenants I have only increased the rent $15 p/wk after 12 mths of relatively low rental in comparison with the market trend, best tenants you could wish for.
Protecting my good tenants is the best strategy, filtering the rest I don't hesitate (like my last one, worst tenant you could have). The new tenant seems great and is long term at this point, time will tell how I manage this one. All you tenants reading this, I am not on my own with this philosophy. If you are a good tenant it is most likely you will not be squeezed financially or otherwise. Also yes there are the landlords who just greed driven, the sought of person I choose to avoid associating with.