That's terrible! Being an avid motorcyclist now since 2003, I do feel for you.
Yes I think their motorscooters in particular have seen better days.
What I would like to know: how exactly did the brakes fail? Was it ruptured brake lines, calipers, pads, master cylinder... ? Any photos to share?
If I'm still around in Tenerife in a few years I might just get into motorbike rentals myself, but I think I've seen too many accidents on bicycles. I'd hate to rent out a motorbike and then see someone crash.
Luckily I've not fallen off yet.
I noticed the rear brake on my bike was prone to overheating soon after I got it. Pressed on the lever and it totally freaked me out when absolutely nothing happened. It felt like the lever went all the way to the floor. That alone could have caused me an accident, because it
felt like the brake lever was capabable of scraping the road surface.
Anyway, I have since upgraded to new braided rear line by Hel performance + new pads + new DOT4 fluid obviously. Removed the pistons & soaked the caliper. The old brake fluid that came out was like brown paste (you know it starts off clear and absorbs water with time, changing colour).