From my experience with the two RIs I've had in my collection. One due to cooling and the other came to me as a rescue really bad. You will certainly know an RI when they are very bad off. Pretty much once the snake gets mucusy they start coughing and trying to spit the yucky stuff out. When it's not to terrible it will sound like a crackle or a pop everytime they breathe. At that point you may be able to raise the temps a bit and avoid any further problems. But when they are really bad off they will certainly need antibiotics and beleive me it sounds so awful when they are that wheezy there's no mistaking it. Both got over them really quickly though which was very releiving bc I felt really awful when the rescued girl was just coughing and coughing and we had to wait a weekend to see the vet. Hope this helps.
Morgan