1--Some sociologists claim that a person needs to feel that they are doing valued and valuable work犯了主谓不一致的毛病.建议改为Some sociologists claim that a person needs to feel that he is doing valued and valuable work.
2--同样的还有when someone are given promotion through their work,改为when someone is given promotion through his work,
3--In some cases an employee is working in a job that suits neither their skills nor their personality.建议改为
In many cases an employee' job suits neither his skills nor his personality.
另外,Of course not everyone enjoys their job in today's life.改为Of course not everyone enjoys his job in today ’s world.
4--a salesman become a marketing manager,he may get job satisfaction.建议版本为：If a salesperson gets promated to manager,he may obtain job satisfaction.
总体来说,文章语法错误并不多,稍显中式英语味道,个别单词使用并不是太准确.不过还行.