They are called spam cans for a reason - and that is my reason for not flying in these particular machines anymore.
Hang on there... It's unfair to brand an aircraft or group of aircraft based upon the maintenance (or not) performed on them. I've owned a C 150 for 30 years, which is extremely presentable, with a very nice interior, and all placards legible - because I keep it well maintained. I fly a 1977 C 182, into which the owner has a total investment exceeding $900,000. I bought it for him as a very presentable, though totally original aircraft. It spent 4 years in restoration/modification. Since I first flew it after the restoration, it has flown more than 300 hours with zero snags nor defects. It's all about the maintenance! A brand new glass plane can be left to deteriorate, while a '70's mass production metal can be maintained and restored to be a delight. "Spam can" is a misused term, when associated with maintenance - or lack of!
If you choose to fly an aircraft with defects, it's all up to you, you accepted that plane. Your preflight inspection is your opportunity/obligation to determine that the aircraft is airworthy, and that you understand what you need to to operate it safely. This might include a review of the maintenance records. If you are not satisfied, don't fly it! If an operator consistently has their airplanes on the lower edge of airworthy, and all of their renters decline to fly until they are brought up to spec, they're going to be maintained. Pilots accepting compromised aircraft are not working toward better maintained aircraft.
In every late '70's and since Cessna, and most other types, the flight manual, in section 2, limitations, will present
every placard which should be legible on/in the aircraft. The aircraft is not legally airworthy if all of those placards are not in place.
If you feel that you can manage a safe flight without that information, you might choose to take the plane, but you accept the responsibility. Light aircraft do not come with approved minimum equipment lists, so the pilot has very little wiggle room to justify taking an aircraft with a known defect. The best example would be a day flight with a known burned out nav light bulb - you're probably okay. But if you have a fuel exhaustion accident, you as the pilot are on the hook, more so if you flew the aircraft with missing placards for the fuel quantity.
Failure to maintain an aircraft is not an offense.
Flying an unmaintained aircraft is the offense. The only way that a pilot can fly an aircraft with an obvious defect, and not be responsible is if there is a false or misleading maintenance entry for its rectification.
We've drifted from the topic of powerplants, but we are solidly in the theme of instructors not teaching new pilots what they are actually responsible for when flying. Assuring an airworthy aircraft prior to flight is a
pilot responsibility. Not actually doing the maintenance, but at least noticing the obvious things, and reviewing the maintenance entries for the aircraft. An aircraft provider who rents out "lesser" condition aircraft, may have instructors who find this to be normal and acceptable. It is not. Pilots must be trained that acceptance of defects should be a rare and considered exception, not a norm!