The Truth About Trust report is based on a survey of 1,600 managers. It revealed that 72% have seen employees behave in both of those ways. 'Badmouthing' colleagues (68%) is the next most common unethical behaviour.
Staff lying to hide colleagues' mistakes (63%) is also among the top 10 bad behaviours at work, as is 'passing the buck' when failing to meet deadlines (67%).
ILM chief executive Charles Elvin told HR magazine a "lack of clarity" around what constitutes acceptable behaviour is one of the main drivers of unethical behaviour in the workplace.
"A clear values policy and examples of what will not be tolerated will help to overcome this issue," he said.
"Unethical behaviours can also be a signpost of wider issues in the workplace such as excessive workloads, blame culture and a lack of trust. Some examples of this include pressure to deliver leading to cut corners and fear of consequences leading to people covering up mistakes."
Elvin added that having a clear "statement of values" is a good way to counter this uncertainty.
"Companies with a strong ethical code enjoy the highest levels of trust both internally and externally allowing them to attract the best talent, the most faithful customers and the most reliable suppliers," he said. "High trust among your key stakeholders means that your business is much more likely to be able to weather any difficult market conditions."
The top ten bad behaviours witnessed in the workplace were:
1. Cutting corners – 72%
2. Lying to hide your mistakes – 72%
3. Badmouthing colleagues – 68%
4. Passing the buck (when you don't get your work done) – 67%
5. Slacking off when no one's watching – 64%
6. Lying to hide other people's mistakes – 63%
7. Taking credit for other people's work – 57%
8. Taking a sickie – 56%
9. Lying about skills and experience – 54%
10. Taking low value items from work – 52%
