Working remotely as a tester is certainly possible, however the key factor is knowledge and timing.
A tester should initially aim to get a greater understanding of:
- the business domain
- the product and features
- the current company direction
- the current direction of features and bugs
- the workflow for bugs and features
- the personalities of developers
- conflict resolution over disagreements
To get this understanding a tester benefits greatly from being a part of the development team, typically embedded within them.
Over time this can then transition to a more remote arrangement for a period of weeks or months. There is still the downside of not getting exposure and interaction with the items mentioned above and over time you would tend to drift away from the company mission, culture, goals, etc. Also people leave and join over time so your initial personal relationships wont last.
A good arrangement can be to work mostly remotely but also be on-site for a fixed time each period, e.g. 1 day a week.
If working 100% remotely you can also level the playing field with how you organize meetings. For example if you have a daily stand-up and half the folks are remote on skype, consider the following: have all the on-site folks use private office and use skype as well and then everyone is a 'box' in skype and you've leveled the playing field and removed the 'in-office' vs 'remote' distinction. Some calls these 'remote in-person meetings' or the like.