Low burn patterns were always considered a sure sign that flammable liquid was used. Now the only thing a low burn pattern means is that an intense fire was burning in that area. However, it could be a host of other things that have nothing to do with flammable fluids. In the old days we spoke of a fire being suspicious. Some of us used to ask what that meant.
People are suspicious.
Fires are not suspicious. It does not exist. Either the fire is incendiary or the cause could be electrical, natural, chemical. For some that comes as a shock. For most of us in the profession it is a welcome and realistic approach.