CMD:  The "homeless" population is really a composite of individuals with different presenting issues.  Just laid off from work; escaping an abusive relationship; PTSD vets; mentally ill; alcohol and substance addicted; mentally and/or physically handicapped; and, as you suggest, some are simply "along for the ride" and wish to live off the largesse of others.  I believe most of these individuals are deserving of our support and assistance to better their lives.  I do agree with you that those who are simply "along for the ride" don't deserve our support.  Even worse, their presence in the homeless population harms those who legitimately need help.  They take resources which could be going to the deserving and, importantly, they alienate persons who then withhold support for those who truly need our help.  

I have no sympathy for what you term "social parasites."  However, I do NOT dismiss all the homeless population as Social Parasites.  Does that many any sense to you?  Gary Crum