I would never set off in a new to me boat (especially from an unfamiliar port) until I had thoroughly checked the boat out, including taking several sea-trials of short duration. However, I have over 40 years of experience in sailing (grew up on boats every summer since birth) and so I have learned what to look for. I basically learned by doing, I learned to sail in a 6' dinghy with Dad coaching me from shore as well as on the CAL 21 that we had at the time. I learned to row by just doing it (tethered by the 30' towline to our sailboat), but I'd been watching Dad row for several years prior.
The problem with people today is that they may try to learn by doing.....but never witnessed the correct way to do things and so never learn from their mistakes! I used to have a 9' trimaran (replaced the 6' sailing dinghy) and it was sort of fixed up on my rather lean budget at the time (HS Junior/Senior with only a lawn mowing job averaging $13/week). The boat taught me SO MUCH since it naturally broke quite often! Let's see...tiller broke about 5 times before I finally made it strong enough, gaff broke 3 times, boom broke twice, the boat leaked like a sieve at the hull/deck joint, mast broke once and I just decided to make it deck-stepped and added standing rigging......gee, why not just run one piece of cable from the port chainplate (actually an eyebolt) up through a hole near the top of the wood mast and back down to the starboard chainplate? Yes, it worked great...........until the sail filled and that cable started to slide through the mast......over went the mast again! Well, that won't work......but if I put a wire clamp on each side of the masthead.....that stopped the cable from slipping through! Oh, then I discovered that turnbuckles with an open hook on the lower end don't tend to stay hooked to the eyebolts when the leeward shroud goes slack......better tape the hooks!
Mistakes can be great learning experiences, and on a small boat are usually low cost! One final bit of confession! That time when my mast broke.....I was sailing without a paddle aboard, or an anchor! In hindsight, I could have easily jumped over the side and swam, pushing the boat to the closest shore (about 50' away!) but I was sailing in shorts and a t-shirt, hadn't planned to go swimming and so didn't put on a bathing suit.......but, I really don't think my Mom would have been as upset about wet clothes as she would have been if I had drifted out to sea! Luckily a couple of guys in a 12' catboat noticed that my sail was no longer visible (did I mention it was bright red?) and came over to check on me. They ended up towing me in.