# How can one say if a model is poor based on RMSE value

I have a general question about the value of using RMSE to see if a forecasting model is poor. I used the forecast package in R to find forecasting models for different datasets and used RMSE for test data to see how far the predictions are from their actual values. Some data sets have values of around 500 for daily number of orders and RMSE for them is around 50s. But I have some datasets that have an average of 100 orders per day and the RMSE is around 10.

How can I say if these numbers for RMSE are high? I just want to make sure that the fitted model works fine and I thought maybe RMSE is the best factor to see that.

I should note that I don't want to compare different models. I used the tbats package in R which gave me the best fitted model.