When looking for a commercial cleaner, there are a few things to keep in mind. 

Here are five tips to help you choose the best supplier:

1. Look for a reputable company with having a good reputation. Make sure the provider has a good track record of providing quality service and is insured also. To hire the best cleaning companies in Montreal, you can also visit https://www.cleaneroffices.ca/locations/montreal/.

2. Request a quote before hiring. Get an estimate of the cost of service as well as specific details about what will be included (e.g., frequency of visits, types of cleaning services).

3. Be clear about what you want from the cleaner(s). Specify the specific areas you need cleaned (e.g., offices, conference rooms, kitchens), as well as any special requirements (e.g., no alcohol, no carpet cleaning).

4. Be prepared to give feedback and ask questions. Ask how often the cleaner has been trained and verified, and whether there are any guarantees in case of unexpected problems (such as damage caused by pets).

5. Get references from previous clients and check them out online. Ask for reviews of the quality of service provided.

With these tips in mind, you should be able to find the best commercial cleaner for your needs!