second hand car

I am thinking about buying a second hand car and would like to know what
should I look out for and clues that it may have problems?

Plus how big a problem is rust and paint bubbles?

 

Before you buy, take the car to a competent mechanic you trust. Ask in your
public library for the issue of Consumer Reports with information on used
cars. It lists the most common problems of the various makes, models, and
years.

It is a big problem. Once rust starts, it is hard to stop. Paint bubbles
are a warning sign of rust, perhaps a car that has been repainted to cover
rust.