ALL dyes are not bad. Just like how mixing new refrigerants with old mineral oils can cause lack of lubrication problems, using the proper dye for a certain type of system is very important. We are talking about chemical reactions with both.
You first want to ensure you are not voiding a manufacturer warranty, then ensure you obtain the proper dye suitable for both the refrigerant and lubricant type. Then ensure you have an applicator that will not fail, even when not under pressure, an applicator that fails can be very messy. Know exactly how to apply the dye by asking others that have actually done it before attempting the job. This is ESPECIALLY true for applications under system pressure!
My bag of leak detection tools contains, Ultrasonic, halide, several types and brands of electronic, big blue soap, several brands of dyes, and the most useful - my EYES. I have found at least as many leaks on systems by first looking for refrig oil and obvious faults such as sketchy welds, pinched tubing, bad or overtightened flares, rubthroughs, cracks, pickled evaporator coils, etc, than I have with any other method.
You really should perfect your leakchecking skills with other types before jumping into the dye pool.
Generally speaking, except for preventive maintenance applications, I try dye applications when other avenues have been exhausted. I have found many leaks over the years that escaped other means as the dye will indicate where the refrigerant has leaked even if it is not leaking at the time I am there.
When applied before there is a leak, a regular inspection with a UV light will catch small leaks before the sight glass or lack of performance indicates there is a leak. It also shows you where to start before pressuring up a flat system with nitro, sometimes allowing you to bypass nitro until the leak has been repaired.
I had a supervisor who took pride in never using a computer by the time he retired. Once he retired and was bored, he started using computers and now builds them from scratch. He proudly said "I have been working for "x" amount of years and have never used a computer and never will, those things cause all sorts of problems!".
The moral of the story is that sometimes you have to look past the "bad reports" of something to find out it's attributes.
As for brandnames, I think highly of Ritchie YellowJacket dyes, dye applicators and most of their other tools for that matter. However I am always looking for better tools no matter what type.
