There is no doubt that the varying quality of private landlords is a complex issue. As such, there are unlikely to be any 'silver bullet' solutions to it. Some landlords are excellent, and take their responsibilities to their tenants seriously. Others, conversely, are content to sit back and take rent from their tenants and will do the least possible in return for this. It is estimated that there are around one million landlords in the UK, of which a vast majority only own one property and nearly all own fewer than five properties. Well, that's according to the Private Landlords Survey 2010, anyway.
However, it is too simplistic to paint a picture of private landlords as being the cause of all problems when the landlord/tenant relationship breaks down. In areas of the country where the property is less expensive (and therefore where rental prices are lower) it is not unusual for a landlord to find that the damage done to a property is far in excess of that which the tenant's bond is able to cover. In fact, in areas such as the South Wales valleys, it is quite easy to envisage a situation where a tenant absconds at the end of a six month tenancy with two months of rent arrears and leaving behind a property which needs extensive remedial work. As the average rental price of around £400 per month, this means that the tenant would only need to have caused £1,600 of damage (including 'normal wear and tear' of any property let, which is acceptable under UK law) for the landlord to be left out of pocket. And that's not taking into account the court expenses which may be incurred from seeking to recoup the rent owed.
Furthermore, the landlord/tenant relationship is often further muddied by the existence of a lettings agent (often unregulated), whose primary objective is to maximise their profits. Basically, by doing is little as possible for as much remuneration as possible. Now, I'm far from an anti-capitalist, but surely there is a need to have a system of regulation in this area of the market to prevent any unscrupulous agencies from playing fast and loose with people's lives?
As a landlord myself, I am quite happy to sign up to a voluntary code of conduct. For that matter, I'm also willing to adhere to minimum quality standards. These could include an undertaking to respond to tenant concerns within a timely manner (obviously, the more urgent the concern the more rapidly it needs addressing). It could also include a minimum standard of cleanliness, and an undertaking to join a registered body (for example the National Landlord's Association). However this does not, in my opinion, address the underlying concern. That is dealing with those private landlords who are not going to adhere to voluntary standards, as they are more concerned with maximizing their yield rather than discharging their responsibilities.
This is only going to be solved by making it more attractive to these people to meet their responsibilities rather than not to do so. Whereas the concept of compulsory licensing provides some benefits, it will be a case of managing those who are already quite good landlords, rather than dealing with those who are the problem ones. Furthermore, it could result in a number of the less desirable landlords 'going underground', thereby creating a system similar to that which occurred during early twentieth century prohibition in the USA. The only long-term solution is to persuade landlords to improve by hitting us where it most hurts us - through our pockets!