For example, a chef connection endorsed me for 'Ruby' even though he doesn't code Ruby at all.
Do you think the LinkedIn endorsement changes your perception on a profile you view?
Recommendations are even more unreliable.
Case in point: A manager who was on the same level as my direct manager contracted an 'Architect' to come up with a high level estimate for a big project. The guy basically drew pictures in Enterprise Architect for 6 months and barely interviewed any stakeholders or technical folks. I was in the meeting where it was decided that it was a worthless exercise and big waste of time/money. We let him go right after he turned in the project plan and scrambled to redo the work. The manager that hired him wrote him a very positive, over the top, gushing recommendation on LinkedIn. I don't know if it was 'quid pro quo' or just the manager trying to save face but it definitely showed me that they are worthless.