How are some girls getting burns from tumescent lipo?

Tumescent Liposuction itself cannot cause skin burns!   It is when you add liposuction machines which use energy to help break down fat cells that you can get skin burns.  It is these machines, Ultrasonic and Laser liposuction machines which can burn your skin.  By definition, Tumescent Liposuction just means that Tumescent Fluid is injected under the skin before the fat is suctioned out.   Which machine is used will depend on the surgeon's preference.  But this fluid cannot cause burns of the skin by itself.       There is however, always the possibility of friction burns on the edges of skin where the cannula slides in and out.   But, there are usually very minor.  

I have not seen burns with tumescent liposuction alone.  Perhaps a heat component is being used, which is causing the burns.

Any method can cause issues- the surgeon must always be aware and protective. Even safe or power assisted or even regular liposuction can cause friction burns at incisions if not performed with great care. Vaser ultrasound, Smart Lipo laser, etc should be very safe if performed by an experienced plastic surgeon. Beware of inexperienced physicians.An exam and consultation with a plastic surgeon who performs these procedures is recommended to confirm you are a candidate as well as discuss your options and expectations.